I'll say this – there are enough people on Quora with similar names already, that anything that distinguishes you from the masses, helps me (the reader) recognize and link your questions/answers together over time, assuming I'm not a follower.
Further, those who have filled in a profile, even a complete snarky one-liner, help me see "what their angle is", or any specialities they may profess or display. It's not a defining factor, it's a helpful guide, just like having a profile picture. It's one step further away from anon, which semi-unfortunately always seems to be a good thing here(*).
Topic bios work like this – if your answer sucks, a good topic bio won't save you. But if your answer rocks, and the topic bio is congruent, the chances of your profile getting a direct visit go WAY up… Because suddenly it became more interesting to see other relevant/related answers from you.
(* In truth, I'd like anon to be that magical thing that allows really tough questions/answers to come to light… But until there's a nice navigation to "best ofs", what I tend to find is that Anons are either hiding their respectable identity to throw down snark or invective, or somehow embarrassed or afraid to be associated with their truly great answers on topics that shouldn't be seen as sensitive or taboo anymore… I've noticed myself upvoting anons a lot less as time goes on. The people who put themselves out there for an 85% answer deserve the credit more from the community than the 90%er who hides behind a mask. Again, this is just based on the roads I travel on Quora, but I do so hate being unable to follow those who really nail an answer in a topic of interest.)