A big part of why this occurs is Electron. Same with any app that's basically a browser app: memory usage is out of control relative to what the application does.
Case in point: https://arcade.ly/games/starcastle/ (disclaimer: I wrote this). Uses 284MB, for a version of a vector arcade game from 1980. Same issue with my version of Asteroids too: https://arcade.ly/games/asteroids/. Some of this is down to the idiotic way the Web Audio API handles compressed audio, but with Asteroids I have to pre-render a lot of images because canvas 2D performance isn't that great with drawing primitives. Even excluding these issues, and allowing for several canvas layers at 1366 x 768 x 32 bits per pixel, double-buffered, and the thing still seems to consume quite a bit of RAM.
Welcome to the wonderful world of JS/CSS/HTML5 apps.