Quora's whole model is "like Stack Exchange, but with venture capital for a big IPO".

Everything after the comma explains why Quora is junk.

Quora is (was) open ended and allowed discussions. Most tech questions I have can't be written on stackoverflow. The most stupid one is "what book can I read to learn xxx".

Now they removed descriptions from questions, hide comments by default, so they are heading the same direction.

Stackoverflow is helpful as documentation with examples, but for engineering problems is of no help anymore. I usually have to ask in some dev chats and discuss there

Exactly this, for the past many years, when ever i have needed a good answer to a not-so-common problem, Stack Overflow cuts right to the chase and delivers a useful answer.