Yeah I think it’s because the Steam Deck is very similar to the Switch, whose sales have been declining drastically the last year or two. Recently a big wig at Nintendo said something to the effect of “we want people who already own a switch to buy a second switch”, a “one in every room” type of deal.
To me at least, playing emulated games on something like a phone is unpleasant, because of the on-screen, touch controls. It sours the nostalgia and is plain ol unpleasant. The controls use part of the screen and aren’t tactile at all.