> But take any successful show in the last few years, it simply could not have made nearly the same audience or revenue on these platforms. The stuff you see there is already hyper optimized for these platforms - it'd be a very poor business decision to take a show with the production cost of TV or subscription services, and monetize it purely on these platforms.
This is exactly it. There are tons of incredible series with high production values on YouTube created on shoestring budgets, but they mostly cater to very specific niches. They can succeed on YouTube because they aren't going for the broad appeal and hyper-consistent development cycle required for TV channels to pick them up. If such an ecosystem existed in the early 00s, some of these series probably would have been picked up and made incredibly successful to a much broader audience by channels like Discovery, History, or TLC, but falling cable subscriptions has resulted in massive consolidation diluting the original premises of these networks, thus forcing them to focus on more generalized content. (The 2007-2008 WGA strike certainly didn't help, but I think this was inevitable with the subsequent rise of streaming services - the strike just kickstarted the realityfication/enshittification of cable TV a couple years early.)
That's not to say that no YouTube series or YouTubers can make it on TV, but they have to fall into the niche of having broad appeal on YouTube without being limited to YouTube, and I think Drew Gooden made this point really well in his video covering Lilly Singh's late night show [0], which got off to a horrendous start because studio execs, blinded by the prospect of getting a popular YouTuber to make a show for them and (hopefully) get that YouTuber's audience to throw their eyeballs at it, did not attempt to create a show that worked for Lilly, but instead shoved Lilly into a tired formula which she floundered in. (Keep in mind that Lilly's core YouTube demographic would be sound asleep by the time each episode aired at 1:30 AM, and one wonders the kind of discussions that led to this show getting greenlit in the first place.)
In a way, though, we're already seeing lots of content which is hyper-optimized for streaming services that is paid for by the big studios - I remember seeing an interview with some writers for a show only available on Netflix (I think, and I wish I could remember anything more specific) who remarked that with broadcast shows, you had to fit everything neatly into very specific timeslots, and that each timeslot had to have a hook to keep you sticking around after the commercial break, but when you're writing for a streaming platform, all those considerations just go out the window, allowing for much easier and more natural storytelling, like a movie.
Of course, you could still air these shows on TV, but they wouldn't work as well on TV as, much like movies that get chopped up for broadcast, very rarely do you have good hooks before commercial breaks. In addition, many shows made for streaming services do not follow the standard 18-22/37-42 minute show length, which means you have to either insert a ton of ads to pad the runtime into a 30/60/90 minute timeslot or have an odd lineup until you can get to some other oddball-length show (or until the infomercials begin).
[0]: https://www.youtube.com/watch?v=lex6USTugUU