I'll preface this by saying that I'm ace so I'm probably biased, but I'm going to go with "no". It's mostly just one of those things that some people see as a milestone, like how some people insist that drinking makes you more of an adult. I imagine the whole inane idea comes from the fact that these things are illegal until you reach a certain age, and the sex thing specifically comes from that combined with outdated stereotypes of men and antiquated views on women. In reality, losing your virginity doesn't make you any more of a man than liking monster trucks does.