That's just the hotkey to close Chrome. It doesn't make it forget your session or anything
It does make Chrome forget all state of the opened tabs. It does make Chrome forget everything that you have opened in an incognito window. It does make Chrome forget everything that you were entering in a text field somewhere. And it so happens that I'm most frequently switch between tabs when I'm doing some research (mostly in incognito window to avoid polluting my cookies) to write some post somewhere. So, when Chrome exits, it is most likely that I have some long post with a lot of references written and not saved, and a lot of other references opened in an incognito window, and all of that (which is hours of work) is lost on exit. Granted that's my way of working, but still.
And also, as you have mentioned, it does interrupt my workflow by using 100% of CPU for, like, ten minutes while it reloads all my tabs. That's if I'm lucky, and I'm connected to a broadband network at the moment; otherwise, it just consumes all my mobile internet allowance, and does not load anything.
quitting by mistake is something that happens very rarely compared to quitting intentionally
Quitting it by mistake is something that happens every time I want to switch to the previous tab (hundreds of times per day) and accidentally press Q instead of Tab.
Quitting it intentionally is something that never happens. I guess that probably somewhere out there is a person who really needs "exit chrome" feature, and even needs a hotkey for this feature, but I am not this person, and neither is anyone I know.
It is an ejector seat in its pure form. Surely, ejecting is trivially reversed by travelling back to base and launching another aircraft, pilots definitely wouldn't want to be annoyed by a prompt when trying to eject themselves by pressing the button located next to the "FM radio" one.