Joy-Con joysticks use a potentiometer to read the voltage at a wiper that slides across a strip of resistive material. That material wears down over time, or plastic and dust can dirty the sensors.
Stick drift is a huge problem with other Switch models. One survey found that 40% of Switch owners had problems with their Joy-Cons drifting, and things didn’t get any better with the Lite or OLED editions. After a bunch of lawsuits, Nintendo’s president even admitted it and apologized, setting up a free repair program for customers in some parts of the world.
Give me a Switch without a screen. No battery. No detachable controllers. Just a brick that plugs into the wall and the TV, compatible with a Pro controller. Probably could even sell that at a reduced price too. Maybe even overclock it and give it a bigger cooling solution to get better performance. Maybe Nintendo’s newer games can actually run at a stable 60 fps on their own hardware finally.
I'm actually in the same boat. I hardly ever play the switch in handheld mode. It is incredibly uncomfortable for anyone over the age and/or hand size of a 12 year old. The form factor is terrible for mobile use IMO. Even when we don't play the switch docked on the TV, we have taken to playing it plugged into a small USB-C monitor on a side table in front of the couch.
I really wish Nintendo would offer a different option like you're saying here. The only thing that's nice about the Switch form factor is the size for portability IMO. Scrap the screen (and probably even the battery) and offer an option that's as small as (or even smaller than) one of those NUC-looking mini PCs that are all the rage nowadays.