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.
I mean, realistically its still Nintendo so I still won't buy it. I disagree with their business practices ever since Iwata died. Nintendo has gone way downhill, and I don't want to give them any of my money anymore. It sucks since I really like the old Zelda and Metroid games, but theyre only games. Its not the end of the world. Plus, emulation fixes Nintendos problems anyway.