The fact that the educated and intelligent are sometimes in the wrong doesn't mean it isn't a good heuristic. Pretty much any heuristic is going to fail sometimes. The question is whether the heuristic is accurate (in the sense of being more often correct than not) and, if so, how accurate it is. This heuristic seems to be one where the general trend is clear. I can't identify a single example other than Marxism in the last hundred years where the intellectual establishment has been very wrong, and even then, that's an example where the general public in many areas also had a fair bit of support for that view.

I'm curious about your claim that that "intellectuals care much more about the status-signaling aspects of their opinions than the common folk." This seems plausible to me, but I'd be curious what substantial evidence there for the claim.