My experience with Quora answers has been that they are blatant ads from people working on different companies.
Just search for anything like "what is an open source alternative to X" and the results will be a lot of people trying to justify why their Y paid option is a good solution for your problem.
In other areas it seems like it's people working on their craft of writing fiction, notably erotic fiction. Questions like "What's the naughtiest thing you've done at work?" generate those kind of responses. Which is fine, just don't expect me to believe it really went down like that.
