Quora is doing a lot of things 'wrong.' Wrong as in, choices that produce a low quality service (eg dark patterns, maximizing for volume of content which has led to vast amounts of marketing spam posing as real content), not wrong as in they have no traffic. They get to play by different rules for the same reason Pinterest does, inside-SV favoritism: Google protects Quora from being punished for all the things they do that directly violate Google's search engine rules that would get anybody else penalized heavily [1]. It has been talked about on HN for many years, it's clearly a different set of rules.

Further, Quora - as with Stack Overflow and Wikipedia - had the benefit of arriving on the scene before Google closed the door to easy SEO, easy search engine traffic. Quora is already inside, entrenched Web bloatware, they can get away with more in part because of that.

[1] I'll provide a prominent example of this Google / Quora SEO fraud in action.

If you check out this Quora Q&A page:

"What makes Napoleon Bonaparte such a famous icon?"

https://www.quora.com/What-makes-Napoleon-Bonaparte-such-a-f...

And then if you, as a human, click on a right side bar of links ("Related Questions"; on mobile it's just below the top answer) - when you perform that action, they blur out your experience and present you with a content blocking prompt that hides all the content from you, attempting to force a sign-up. One of Google's fundamental content rules is that you must present page content to them, to their bot, the same as you do a normal human user of your site. If you violate that, much less do so egregiously, they'll penalize your content heavily. Do you suppose Quora is giving the Google bot that same experience, blocking Google bot's every attempt to crawl from page to page and trying to force Google bot to sign-up using a dark pattern? Of course not, and thus it's fraud in action. Google doesn't give a shit because they have zero integrity as an organization. It's one of the more blatant examples of Google hypocrisy as a search engine and it has been on-going for many years now, and pointed out constantly in tech circles and yet it persists, so we know Google is doing it with full knowledge and intent (thus it's an inside-SV favoritism action, Quora gets to play by different rules than everybody else).