Sometimes I do read the comments without reading the op, but then I won't comment, unless it's something unrelated (like this very comment, for example, even thought in this case I did read the OP).
But yes, there's plenty of "Didn't read the article, but...".
I always feel somewhat bad when I do this, but it really is much easier to read the first few comments. For really long articles, I often only read the beginning, catch something I want to comment on, and hope I didn't need the rest for my comment to be valuable.
It's not great, and honestly feels a little like in high school when you didn't actually do the full reading assignment for english class, but it can be hard to keep yourself to high standards.
It's something we do on Lobste.rs. Its guidelines allow a short, purely-factual description just to save people time. On CompSci papers, I always put the abstract in there either whole or trimmed. Some people TL;DR the articles in their comments which happens here, too.
Allowing a super-short summary might be a good practice here, too. Especially for long articles or videos. On videos, maybe link to transcript or slides, too, so people don't have to dig them up. It's another thing I try to do over there.