Its easy peasy with Qt as well. I am the only dev for https://www.sostronk.com/app and it looks (and behaves) _exactly_ as our designer wants it to. (Oh, and this is when I'm also spending time working on backend stories).
> no one cares about efficiency anymore.
That is not true. Discord and friends spend a lot of time for efficiency because they're using Electron. It is not impossible to have a (relatively) efficient application with Electron (VSCode for example), it just takes more effort. Compare that with Qt where performance is free of cost - in the last 5 years at SoStronk, I've hardly ever needed to spend dedicated effort for improving performance. Another example, and I wasn't aware of this till very recently, is the Telegram Desktop app which is Qt as well.
But yeah, I do agree with your first point, the only reason Electron is in use is because JS developers are a plenty. At the end, cost is the #1 thing when businesses make decisions.
Several things I can think of: "quantity is not quality"; JS developers far outnumber everyone; making web apps look exactly the way they want is easy, and they are not interested in platform-native functionality, preferring a "consistent" UI across platforms instead; "premature optimisation" dogma that means no one cares about efficiency anymore.
Microsoft Teams and (later versions of --- they actually moved away from perfectly decent native Win32) Skype also use Electron, and that's Microsoft. That says the size of the company and its resources matters little in things like this.