"No one" is an exaggeration; there are OBVIOUSLY people who love repeating themselves, and obviously people who simply don't mind it.

I hate it because I speak as precisely as possible. If you don't understand me the first time, then there is literally no way you can understand at all.

Also, some people really do pretend not to understand you. It's a way of gaslighting you into believing you are "incoherent", and/or gives them an excuse to ignore uncomfortable truths.