Idk, most Windows users expect Linux to be for hackers only and won’t switch. So, I think, we mostly have power users using Linux and they should be expecting this behaviour.

A standard between OSes? No, I don’t think so. Even Chromium and Firefox differ slightly, according to someone in the Mozilla thread. Pressing the middle mouse button in Edge doesn’t open a Link in a new Window, you just get the weird page scroll thing.

I don’t know about macs, never really used one. But didn’t they even try a single button mouse with a touch surface on top? (the magic mouse?)