I sincerely think it’s broadly accurate - that, for the Republicans and especially for Trump, (most) every accusation is a confession.

There’s a simple psychological element to it, most often illustrated by moralists who rail against perversion of one form or another, only to be revealed to be perverts.

There’s another aspect to it though, and I think this is more often the case with Trump specifically - it’s a way to proactively undermine someone else’s accusation against you. If you can get your accusation out there first, then they end up sounding sort of like a child saying, “I know you are but what am I?”