I had that impression mostly when I went back and read some old OB comments - for example, a lot of comments on Archimedes's Chronophone seem to just miss the point of the article.

I would expect the same post would get higher-quality proposals today - but then, maybe it's because the set of LW comments I read is biased towards those with high karma. Or maybe it's because the threading system makes it easier to read a set of related comments without getting confused.