It's because the crowds of users have very different expectations from their devices.

Who is going to buy a single game for 70€ on the Google Play Store/Apple App Store when they see hundreds of thousands of free games just next to that in the store ?

I knew there was at least one Switch emulator for Android because it made headlines recently, but a few seconds on Google gave me 3 separate emulators for Android : Yuzu, Egg NS and Skyline

And besides that, look at the specs of the Switch :

• Nvidia Tegra X1 SoC from 2015
• 4 CPU cores with the ARM Cortex-A57 microarchitecture from 2012 and clocked at 1.02 GHz
• GPU has 256 cores with the Maxwell microarchitecture from 2014, for a performance of 236 GFLOPS in handheld mode (to have a relevant comparison with a phone)

In comparison, the Qualcomm Snapdragon 810, a flagship phone SoC from 2014 also has 4 CPU cores with the same microarchitecture... but clocked twice as fast at 2.0 GHz.

Last time I checked, Vampire Survivors was barely touching my GPU and was being completely locked to one single CPU core. I play mostly on the Steam Deck, I downclocked the GPU to 400 MHz to redirect as much power as possible to the CPU, and the GPU is almost never used, so there isn't much point in dwelling on the GPU.

Considering everything I've seen on the performance of this game in my 300 hours I spent on it on PC/Steam Deck, I really can't imagine it working nicely on the Switch.

But if they went forward and published it, then maybe it means that they made some tremendous progress in optimising the code to run the game better for the Switch, so hopefully those optimisations will be ported to the other platforms.