>>123949681Production funding is the main thing, I'd guess.
Making a show more advanced than a flash animation is more than most can do alone. And affording voice acting.
That can change 'now', to a point, with patreon and crowdfunding. I'd say ads, but google will take any reason it can get to not pay you.
The issue with that is that you'd have to make things out of you own money at least at first, and hope you can drum up enough support to at least start breaking even.
The secondary reason is a stupider one, but I'm sure it traps some people.
Studio production and television runs probably just give a more 'legitimate' feeling to the whole thing.
Telling someone you made a tv show for Nickelodeon or Disney probably makes you feel a lot more important than telling someone you made an indie cartoon on youtube, even if the show is identical, with identical success.