Because of the wonders of Linux. Once Gabe conned the industry into seeing Proton's potential, it was a wrap. You have a matrix train shelf of different versions of Linux all for free 99 and the fact that they don't feel like bloat is amazing in itself. Windows feel like a oversized tumor holding shyt back, especially gaming. Then you got to factor in denuvo that's in most video games, the shyt becomes a frustrating slog of events.
This is why Windows based handhelds are in a weird place, because they reek of those old palm OS handhelds that couldn't go beyond the limitations, including the software.
What makes the Steam Deck amazing is the fact that you can do almost everything on the machine, and the customization can give you tons of mileage with the games.
You want 60fps, lower the settings or hook that baby up because lmao battery life.
You want to preserve the battery, Steam OS gotcha with a locked 30FPS option.
The only reason why I would get a Ally is to replace my laptop since I can just hook up a KB/M to a mini hub and keep it Gucci