It definitely has to do with quality. Firstly, Nintendo distinguished themselves from the competition starting with the NES through quality control for the software titles, resurrecting the entire US market after tons of shovelware saturated it in 1983-85. By the time of the 16-bit consoles, Sega specifically profited off of allowing stuff that Nintendo wouldn't, like more violent games. Nintendo's legacy of quality family-friendly titles is pretty damn obvious, and when one is buying their console, they's also buying into this ecosystem, knowing that they'll have a new Mario Kart game to play with friends. And, of course, knowing that the friends are likely to be familiar with Mario Kart.

Secondly, you'd do better by citing any examples of indie devs providing hardware and software of equal quality and innovation to Nintendo's, instead of empty statements. For example, Playdate is an interesting handheld console that definitely looks well-made, and is designed by Teenage Engineering known for music gear like synths. It has a crank on the side, and aside from that, a d-pad and four buttons, a black-and-white screen (not grayscale) with 400×240 pixels, a 168 MHz CPU and 16 MB of RAM. It costs 230$ (originally 180$) with twenty-four games, and 40$ for twenty-four more. I bet most of the games are retro stuff like platformers. Do I admire Teenage Engineering's output? Oh yeah. Would I buy this if I had 270 spare bucks for a handheld console? Fuck no.

I also had an R35S gifted to me by someone more than a bit into emulation handhelds. It has way better specs than Playdate and okayish quality of the inputs. Only, the battery went fully and irreparably dead after a year of it lying around, and moreover, the battery may be pierced by the screws holding the case in place when the battery expands with age, leading to a fire.

Guess what my primary handheld emulation device is? A PlayStation Vita gifted to me earlier by the same person. Reportedly it can lie about for months with a game paused, draining barely any battery charge.