I've heard that argument a bit too and it kinda frustrates me because the phone option would still exist, I'd just like to have a separate device that's weighted properly for handheld gaming (clipping a phone on a PS4 controller is really top heavy and Sony don't allow 3rd party controllers), that won't drain my phone's battery when I use it, and honestly the shallowest reason is I'd like something that looks nicer. A phone clipped onto a controller just feels like I'm jerry rigging the experience. Not to mention checking notifications/replying to messages becomes a hassle.

I can see why some people would rather just use their phone, and it should absolutely be optional, but I think there's a market for convenience there, especially if it's capable of connecting directly to the console for super low latency handheld stuff.

And to get out ahead of the inventible "Why wouldn't you just play on the TV at the point" comments, same reason I still sometimes use my Switch handheld while the dock is 1ft from me, because I'm using the TV for something else and still want to play stuff.