No trolling about the statement, the stated screen size of any device with onscreen buttons applies to the whole screen without the buttons in use, call up the buttons and you lose part of the available screen real estate. Then you have the added issue of some apps not displaying properly with onscreen buttons. Capacitive buttons don't impact the stated screen size or app usage, what you see is what you get all the time.
The problem here is, as always, Microsoft and their incompetent programming skills which prevents them from coding appropriate behavior when capacitive buttons are used on a device, ie, dimming them when watching videos, disabling them when gaming. Samsung actually did the latter on one of their phones and proved it could be done but Microsoft has chosen to take the lazy way out now and just ditch capacitive buttons altogether.