That's all I ever read. I only follow a small number of people who produce high quality content related to my industry, though. Perhaps that is what primes the "For You" page to say within the same realm and not go off the rails as you suggest?
I'm sure you are right that garbage in, garbage out applies. But why feed it garbage?
In the old times, you could see _why_ a tweet appeared in the stream (as in x follows, y liked, z replied) so curation could happen. But that's gone because musk finally figured out that him liking porn tweets was public.
Before I could say "I don't like edgelord content" and that class of tweet disappeared.
Hence the utility of lists for me. It allows me to follow people who regularly like content that I hate, but allows me to see what they tweet.
So, you are indeed right. I think I follow more than one subject, which causes the issue.