thanks @Shepherd for the suggestion. We've thought and tried limiting questions and answers to logged in users, but it only makes people shy away.
So far, them being anonymous hasn't affected the platform in an extremely negative way. As in, no spammers yet. 9 out of 10 are genuine people seeking answers and the spammers we delete as soon as we detect.
Once spammers start winning this war, we'll definitely disable anonymouses