The mods can turn comments off on posts, but rarely do. I think, if we want to broaden the kinds of stories that can survive without flagging, that should happen more often.
You have some very strong opinions about what kinds of discussion are suitable. Fortunately, those opinions are not universal.
Turning off comments kind of defeats the purpose of the site, to my mind. It's no fun when moderately voted links that generate no discussion park on the front page for extended periods of time as already happens.