I hate Electron apps as much as the next person, but it's indisputable that to get a simple desktop app deployed, Electron is easier, and to me that signifies that it serves a purpose, at least in the prototyping space.

I have like 10 ESP32's lying around my house, they're fun to tinker with, but my Raspberry Pis get a lot more attention from me because there is a substantially lower cognitive overhead with them than the ESPs. If I had a plan on selling my stuff, then yeah, the Raspberry Pi might be overkill and I'd consider going for an MCU module. However, for a fun little DIY project, I don't see how an RPi is a problem.

EDIT: Realized I forgot to mention another point; not everyone really wants to muck with pointer arithmetic for simple things; this app was written in Python, and as far as I know, the ESP32 chips are mostly C/Arduino; I realize that there exists NodeMCU and such variants, but due to the Raspberry Pi being "Just a computer", you have access to virtually every language under the sun.