This has all the hallmarks of one of those changes driven by single-minded metric chasing (engagement!) instead of principled reasoning on what the product should do and feel like to use.
That said, i also think production value in popular channels has really skyrocked the last few years. We've entered kind of a golden age for user generated content, for better or worse. It is very entertaining but very much more addicting.
For example, i watched a guy for years who reviewed classic synthesizers and made silly songs. He has recently made an entire 2hr documentary on the history of ARP synthesizers with engineer interviews and everything! It is like some Ken Burns level stuff https://www.youtube.com/watch?v=l31RXiVSI9s Nothing on youtube existed like this a few years ago. It is an amazing world we live in now.
I can't imagine trying to administrate / police all of the people / content on youtube. It's an impossible task. There are hundreds of millions of users with thousands of hours of content being generated every second of every day. It also cost more to run than it generates, so it's practically a public service. I wish there were more customization for recommendations though.