It increases the cost of all menu interactions with non-focused app by one click. I'm not sure if gnome 3 duplicates that menu bar on each monitor, but if it do

It increases the cost of all menu interactions with non-focused app by one click. I'm not sure if gnome 3 duplicates that menu bar on each monitor, but if it doesn't then it means significantly more steps (strictly speaking) to locate the app, locate the menu bar, return to the app. It also encourages a poor menu paradigm (imo) of nested menus. Iconography, ribbons, searchable action bars, and other innovations are more often found on OSes where the choice isn't made for the user. It seems really silly with how UIs have evolved to use a Mac at work, with half of the menus in the app and a seemingly random other half in a disconnected set of nested menus. That's my experience at least.