Which makes it impossible to replace a selection by pasting. Also, except for terminals, it typically pastes at the pointer location, so you need precise aim (emacs thankfully lets you customize this, but UI toolkit widgets usually don’t)

> Which makes it impossible to replace a selection by pasting.

In principle this is false with a Plan9-like model of mouse chording. Holding left click over a selection and tapping middle click is a reasonable solution.

But for those cases you just use cmd+v or whatever

Yeah, and I keep pasting the wrong thing because the terminal emulator tries to simulate the X behavior (which is very useful) but doesn't maintain a separate buffer like X does.