Except "struggle" is entirely subjective. In fact, outside of a few things that causes physical dependence (which vary in length except they all, eventually at least, end), the concept of addiction as used by the government does not necessarily match up to how those in the particular field of research would. Government makes laws and laws prefer bright line rules. Something like "did you, without authorization, use the credit card given to you by your company to make purchases unrelated to your work", for example, have concrete, definable, and answerable elements that are universal and more or less binary, provided that the statute has a definition section that makes sense. But "so addictive" or "designed to be so engaging and as a result people are by and large struggling to exercise personal accountability and it is causing adverse health outcomes" is pretty much the antithesis of that. The government would need to define "addictive", "designed" would need to have an intent element (one designs the software, sure, but you're asking for not what the software itself does but one step further - what its impact is on the population at large). How does the government prove that intent, especially since criminal law tends to define intent as intent to act which combined with the act itself, creates the crime. What counts as "so engaging" or even "engaging"? Does it require active engagement? Plenty of platforms do not require any active engagement to partake in the conventional sense, unless reading is engagement. How many people counts as "by large" (I assume that's what you mean, feel free to correct)? How would the government show that the product and any struggle is causatively linked and not merely correlative? How does one define struggle to exercise personal accountability? Where did the duty of exercising personal accountability even come from as to establish liability and would that criminalize those who are disabled or injured as to being unable to exercise such responsibility writ large? And what counts for adverse health outcomes? All these need to be worked out in legislation and likely argued over in court. Every single element needs to be worked on as to not to be overly inclusive or exclusive. And since it's the government, the consequences for violation is without question enormous, and therefore, anything that can be misconstrued can result in the ruin of a company or persons in a variety of ways, but do you really want to have the government determine who is an edge case that doesn't count? Because the government have done that based on assumptions of potential harm and it has caused what today would be considered horrific abuses of human rights and very little positives beyond enriching those whose income derives from the enforcement of the government's scheme.
Laws are lagging indicators but they also last a long time. the CFAA was passed before the advent of the WWW and it took until 2021 to even set a basic check on the part of the Supreme Court that effective set the ground rule that to access what amounts to a computer linked to some network beyond authorization, an authorization scheme needs to exist in the first place. Before that, one can easily be charged and even sent to prison or be assessed massive fines when there's no meaningful distinction between what is authorized and unauthorized space. These were not problems in the early to mid 80s but when problems did arise, it still took a quarter century to resolve. To have one future-proof goldilocks solution is already next to impossible, but you're asking for five or six stringed together in order to have a sensible law that is well tailored enough so that it is effective without being oppressive. Not to mention that unless the behavior is generally abandoned by users, it creates black markets that are simply illegible to the state. The government then effectively loses control over what it purports to control to those with means, leaving only those without subject to the full force of the legislation.
That of course all predicates on the premise that there can be commonly agreed and sensible ways to define all those, and it is in the best interest of the government to do so and passes Constitutional muster not just on speech grounds but a host of other potential issues, like, is this a purely civil matter or a purely criminal matter or both? The federal government can treat this explicitly, or kick it off to an agency as part of its mandate, but which one? Do we need a new one? Are there checks and balances that would provide some sort of agility that keeps up with the times? What if new research comes out that shows the lack of a link, but by legislating it, you've effectively frozen the relevant conclusion in time. Enforcement creates constituencies who do not care about science or potential upsides. The DEA is on the record in the federal register that patient access to legitimate medication is secondary and effectively an afterthought to enforcement of supply, because the agency's mandate presupposes that substances need controls and are presumed harmful and that enforcement, with the teeth provided for by the DOJ, will trump any study the FDA or our academic institutions can ever show. By the time that particular moral panic was given a name, the US government had been attempting repeatedly to use prohibition as a way of imposing a specific set of social mores that at first was a pretext to target specific racial minorities and when that became socially unacceptable (legally it was unacceptable under the 14th Amendment anyway, but they effectively smuggled the laws in through the Treasury Department and protectionist regimes by taxing the goods into oblivion, and avoiding the tax obviously is also a violation of the law).
In that sense, the government operates very much like a machine, whereas given a concrete goal to achieve and it can likely achieve it, but the manner by which it achieves it may create additional problems and convoluted interpretations that ripples through history in ways unimaginable. The loudest voices in the room, or those with existing financial resources or interests, can use the rent-seeking system known as lobbying to shape the laws to begin with. And where does the fines end up? Certainly in most cases they are not given back to the community, but end up enriching the enforcement agencies. Go to a police auction and see how much they're raising from the sale of "proceeds of crime", except not all of it are crimes that are proven in court, and much of it are crimes without specific victims and so, it becomes a regime of appropriation of private property to enrich a few in the public sector.
There's usually an annoying gap between concept and reality. In isolation you want a policy that can solve problems in a targeted and fair way. In reality it almost never happens.