I'm familiar with the subject matter. I'm not familiar with the author.
I love classical music. I've been singing in a choir since I was 7, playing the piano since the same age, and compose music myself (https://youtu.be/7Tex-OUk6ZM). I’m actually on my way to church right now to sing some Howells.
I use Spotify every day
I use AI every day
I have enough familiarity with the subject to have an opinion and express it. I'm sorry that I haven't read the author's book.
You're not wrong. If comment sections were restricted to people who knew the subject matter AND the author, it would be empty indeed.