I don't think the vast majority of people installing Windows on the Deck are doing so because they "don't want to learn Linux".
KDE Plasma already looks roughly like Windows 10 and is similar in usage, and Steam Big Picture (Game mode) is completely agnostic to the underlying OS.
People install Windows when they want to play games that only run on Windows. Someone could spend 4 years becoming an expert on the Linux kernel, they could start making custom drivers as their morning puzzles for fun... And they still would need Windows to play Call of Duty Modern Warfare 2 on the Deck.
I dual boot because it's just way easier to get some games running from Epic or Game Pass on Windows. I use Linux just fine, but don't want to have to fight anti-cheat systems if I don't have to.
People install Windows when they want to play games that only run on Windows.
It's this primarily.
Secondarily Linux is still a pain in the ass in a lot of ways. I've been playing with Linux for a few years now after being exposed to it at work. I love Linux but when I dual booted (Ubuntu) and tried to daily drive it a year and a half ago on my desktop it was a nightmare. I literally came back after one day and nothing worked. Sometimes I'm down to troubleshoot, sometimes I just want games to work. Granted, Proton has come a long way and most of what I try on the Steam Deck just works.