Yeah, I agree. My comment on your post was unclear. Although "nice post" can be spammy, it's not something I'd flag unless they were commenting that on a whole bunch of posts that they clearly didn't read. Even then, I'd probably comment something like "you should stop spamming posts, otherwise you're going to get flagged."
The types of comments I'd flag are the exact ones you talk about in your post.
I actually received one of these comments here in this post. "Thanks for sharing." I looked. Literally hours of the same comment over and over. They clearly did not read this post. I didn't flag, but we've both been here a long time, and we're familiar with the culture. A culture many take pride in and I believe it needs to be maintained.