They were supposed to optimize for the situation in which they weren't the only program running on a computer, and they failed to do it.

Can you blame them? Users didn't care. Heck, developers didn't care - look at how popular vscode is.

Honestly, despite being Electron VSCode manages to outspeed every other editor on my machine (by qualitative metrics), even stuff like Zed (which manages to lag on stuff VSCode doesn’t despite performance being its main selling point)

Revealed preferences aside, every dev comment section for 10 years HAS been full of people loudly insulting Electron.