At one point Quora literally paid people to ask questions. They replaced that with an AI generating questions. Both went about as well as you'd imagine.

Questions drive traffic. They give the answerers something to write about. (The AI version is literally called the "Quora Prompt Generator". It's a writing prompt.) They don't care about the "life" of the site. They care that it has high SEO placement so that they can show you ads.

Some of its SEO is due to the fact that they used to be an attractive community. But having achieved that, they have little need to nurture it. They can coast by on name recognition, at least for a while longer.