I finally got around to reading @pluralistic's essay on why the internet is getting noticeably worse:

https://pluralistic.net/2023/01/21/potemkin-ai/#hey-guys

The long essay is worth a read, but handily the TLDR is in the first paragraph:

"Here is how platforms die: first, they are good to their users; then they abuse their users to make things better for their business customers; finally, they abuse those business customers to claw back all the value for themselves. Then, they die."