This also hit me after a couple of nights with the system by myself when the girl is sleeping and I still want to have a beer and chill. When I first read about the device, I was thinking to myself that "why on earth? This is the most useless device Sony could think of, when you have RP on phones, PC's etc". How well the system works when travelling or wanting to share the TV is miles and leagues above any other RP setup and it just works.
I ate crow hardcore.
It's one of those devices which enables way more flexible way of playing games while respecting others. Like you said, I can play on the living room tv as much as I want, but when the girl cozies up to me, I don't have the gall to tell her to piss off unless she deserves it. Now I can continue my shit while she watches random Netflix stuff that I have no interest in. I can play in places I didn't think of previously.
It's the world of HAVING the possibility to play your PS5 wherever, even if you won't. That's quite a perk. Trust me, there will be a lot of these for sale 2nd hand after the holidays as many won't find use to it, but for those where it soöves problems, it's a great device.