Earlier quoted context omitted.
Text width is important, but this is not a solution, zooming and changing browser window geometry is.
Mac OS (and some linux desktops) seems to really expect you to manage windows by having them always be full screen and swiping between desktops. Which makes changing browser window geometry sub-optimal. Even on desktops where it's reasonably easy, it's pretty annoying to have to resize the window when you go to different sites to get them to format properly.
That hasn't been my experience at all, in fact for me macOS works better when windows are mostly sized to fit their content. Windows and Windows-like Linux DEs is where I feel pressure to maximize everything.