Though I generally agree with all of your bullet points, I will defend YT comments for a second. I follow some YTers that have a good community. I really hate calling it a “community” because it feels cult-y or something, but that’s what they call it. I follow a few people who talk about books and I have gotten a lot of my favorite reads from comments saying “X book is similar to the one you discuss but has better characterization” or something. I don’t really interact with the YT comment section, and I’m certainly not going to join a YTers discord, but sometimes it’s insightful. It’s hard with general book communities because you end up with a mix of people who think Twilight is peak literature and people who won’t read anything written after 1900. At least if we both listened to a 2 hour video essay comparing these two books I know their opinions align closely enough with mine and the YTer that I’m more likely to enjoy what they enjoy. I can’t tell you how often I would get a suggestion from a reddit book thread of if you like X try Y and the suggestion was maybe thematically similar but just a million times worse. Truly it’s like people think because two books are about space or a dog that you’ll like them both. It’d be like suggesting a book about Old McDonald to someone who enjoyed animal farm. Made me so unnecessarily upset that I stopped even bothering with Reddit suggestions. I still get upset thinking about the hours I wasted on truly awful books because of randos on Reddit.

Also, sometimes I’m unfamiliar with a video essay topic and depending on the YTer the comments are a good place to get clarity on points of confusion because I’m definitely not the only one with my questions.