Yes and no. Art school really does help some artists because they need to learn the fundamentals. It's like music: can you be a successful musician without knowing music theory? Yes. Can you know music theory really well and be an unsuccessful musician? Also yes. Does knowing music theory make it a lot easier to be a successful musician? Yes.
Going to school also exposes you to industry veterans who can help you - not just as referrals or networking, but as legitimate mentors. John R. Dilworth (creator of Courage the Cowardly Dog) credits Howard Beckerman for helping his career as a budding animator.
I'm sorry if I sound like a broken record for people who've heard me say this before, but, here goes.
My Brother is a professional animator/VFX artist.
It's his sole source of income, not a hobby, not a side-hustle, it's his JOB.
He went to art school in the early 00's, a time when, by the maturation of the internet, everything you needed to "know" to animate was out there, for free.
He also felt a lot of his class time was a waste due to sub-par instructors who felt a bit highly of themselves despite having very limited, if any, credited work.
But, it was still needed.
He wouldn't be where he is today if not for it.
Why?
The one thing art school does that no amount of at-home self-educating does? Is teach you how to do, well, two very important things, really:
1. Work to a schedule (it must be done to THIS standard by THIS time or you lose, no excuses about how you couldn't adult that week accepted)
2. Work to the request of others (You don't find a place that you just plug in your "style" , you create the "style" your client wants)
These are things that break 90% of aspiring animators/artists, because they can't do it.
They either aren't good enough (or too lazy) to produce work fast enough to meet a deadline.
Or (and harder to detect/correct outside of a classroom) they couldn't break down animation/art to a fundamental level so that they could draw what a given client was looking for, not what they "wanted".
That's the real thing that separates amateurs from pros - can you, if handed a model sheet, draw character "X" in "Y" situation? No "well, I don't LIKE that design". No "well, as long as I don't have to do his hands like that". No "Well, I have issues with his shirt, it's problematic" Just "Can you do it?" and "Can it be finished by the end of the week?"
If yes? You're in.
If not? You are a hobbyist and need another line of work to pay your actual bills.
In essence, art school is needed to prepare you for the reality of what the professional art world will be - It won't be taking commissions of only what you want to do and only on your terms, you'll be competing for work with dozens of others and if you win that contract, you'll be spending a lot of late nights in dark bedrooms binging on coffee and streaming loud music to stay awake and get it done and emailed off before time runs out.
The washout rate in his class was astounding, the graduating class, including him, was THREE people.
THREE.
Over 50 had started...
That's why schooling is still more or less required - if you haven't been exposed to tough standards with final drop-dead dates to meet them? Then you haven't really been taught as a for-hire artist should, and all you'd be getting was a useless piece of paper for the wall that says "Yes, you can trace anime characters better than the average person" .