By mentioning that my shorts sometimes slide down during long rides, I'm not saying that this happens frequently or that it is a drastic thing. But there have been times in the latter parts of a century, especially on hot days, that my shorts would move down just enough that the chamois moved away from an ideal position to control sweating and chafing. Bibs prevent that for me. YMMV.

I am quite OK with the fact that some people don't like riding with bibs. It just happens that I do.