How is it inconvenient? It prevent accidental quits!

I use ctrl-q as my shortcut key in tmux. I can't count how many times I accidentally sent that into the wrong window :) I consider showQuitWarning in Firefox a necessity.

IMO, no application ever should quit from one key combination without confirmation.

I'm guessing Google apps like Hangouts and notifications. To keep you from accidentally completely closing.

On Windows it silently keeps running in the background most of the time if you have apps or notifications running.