There are plenty of supposed Steam Deck killers available in the portable gaming space, from the Asus ROG Ally to the Lenovo Legion Go and all the Ayaneo and ONEXPLAYER devices in between. But none of them have managed to outright slay the dragon that is the mighty Steam Deck yet.
I think there is an argument to be made that if you want to develop a game, for example, for the PS5 you can rely hone your game to the PS5 hardware and it could be extremely stable. This is not possible for PCs because PCs do not have fixed hardware.
However I think this was true in the olden days of the SNES where games where not glitchy compared to DOS gaming where hardware compatibility was all over the place. You can see this on YouTube channels like LGR where finding a compatible sound card is a challenge.
But like you, I don’t find that this is still true for modern PC gaming.