The Series S is an excellent portable gaming console, whether someone chooses to invest in a screen for it or not. Some people do indeed move their consoles, especially those who travel a lot. But of course because no-one who you know does this, then
no-one does, right?
Everyone has 70'' TVs and that's the only way they could ever possibly play games.
It's also a much more unobtrusive looking piece of hardware than the PS5. Someone buying a console for the first time will be much less likely to balk at the size of the Series S than they would the larger consoles.
Older audiences will often have adult financial responsibilities and may be
less inclined to spend money on a more expensive console when there is a more cost effective option which allows them to play the
exact same game.
As for your final line... I can't imagine why you're so desperate for MS to pull the plug on Xbox before the GTA 6 launch.