Hollywood is filled with board rooms of groups who are all incentivized in a way to 'get buy in' through concessions.... the first concession is the art...the vision....
then the talent....
then it's all down hill from there
This pipeline isn't exactly unique to anime. The book -> movie pipeline is very real in western media. The big difference I have noticed is actually that anime makers tend to be less visionary than western movie makers, and instead give you a much more faithful translation of the source material to the TV screen; whereas Hollywood adaptations tend to take much more creative liberty (usually for the worst).
Funny, I've heard the exact opposite complaint a lot, that every anime in the last 20 years is made by committee and that's why the vast majority of anime are just slavish adaptations of already-successful manga, and even the few original anime projects that happen tend to be retreads of genre cliches.
Like there are no auteur anime since 2004?