This is a bad post.
1. It complains about downvotes, which is one of many reasons your post is grey.
2. The main reason people throw electronics away is not because they break, but because they become obsolete: Big [citation needed] on shorter time scales. For longer time scales it's intuitively true but irrelevant. With Moore's law being toast, most hardware upgrades are extremely incremental. I don't get any more battery life on my iPhone XS Max than I do on the 6+ it replaced, it's not any more responsive, etc. Beige boxes haven't been a thing for decades. But, people holding onto their devices longer would absolutely result in less ewaste.
3. When you tell companies they have to build things a certain way, you remove the option for something better to evolve: That depends entirely on the nature of the requirements. Nobody's talking about the government dictating the whole BOM. No innovation is being stifled by requiring, say, user-replaceable batteries, unless we're talking about innovative ways to pad the company's bottom line. Let's not lose sight of the fact that repair-hostile design absolutely benefits the company and only the company at the end of the day.
4. baring the extra engineering/documentation costs: which are already done internally, so those costs are irrelevant. Every company that does repairs has documented repair procedures for their own people already. They can put PDFs on a freaking website. No idea what you mean by "extra engineering costs".
5. forcing companies to create small quantity B2C supply chains and retail channels for consumers to purchase individual parts on obsolete models would be an absolute nightmare: That's somewhat fair, but there's no reason it needs to be any more of a retail channel than their ship/replace stuff already is. The infra is already in place, they're just shipping out parts instead of full devices. I think the word "obsolete" is doing a lot of heavy lifting here.. a 2 years old phone is only "obsolete" by manufacturer fiat, because they can make more money by marketing tiny, incremental upgrades and simply refusing to support the still-useful device.
6. You'll just be cloned by an army of chinese competitors even faster: Not fast enough for this to be an actual concern. Shitty chinese clones happen with a quickness even today, yet for some reason people still spend billions on name brand devices. I do not foresee this meaningfully changing. Trademark/import law is still a thing, after all.
7. incumbent big companies may simply use this regulation as an opportunity to entrench their position in the marketplace: This is a weak meta-situational argument used by all big businesses against any and all business regulations. I do not see why this case is special.