I typically read either on mobile, where reader view is a single tap. On Desktop if it’s too wide (and it rarely is since I browse at 150% zoom) then popping the window to one side is generally sufficient (two taps: Cmd-Right), and if that’s not enough, follow up with Cmd-+.

To be honest I never notice this particular problem because it’s easy to mitigate. The one I do notice is when someone creates an unnecessary minimum width so all the text doesn’t fit. I’m not a huge fan of max width either but it usually is a pretty minor annoyance.