The fact is that Electron is a good platform for ONE application. Once everybody jumps in and makes their application with Electron, and all applications running in your machine are electron, then you as an user have a big problem, basically no battery life.
I wrote an incomplete PopcornTime clone with QML, I've also practiced by cloning the UI of some known apps such as Slack and Spotify, it was very pleasant and immensely saner in terms of resource usage of the machine. But alas, yes, you need to know C++, and that means you need to know about memory managenent and fine details of how things are done under the hood (although maybe that one is not a bad thing at all...)
Electron is a memory hog and a weird platform given it ships with so much overhead, sure. But it's fast to develop on, and with modern machines you can run multiple electron apps at the same time. There's just no viable alternative - building a cross platform desktop app without it requires going back in time 20 years and having to learn a bunch of complicated nonsense about memory management and object lifecycles (and I'm saying this as someone who knows said nonsense fairly well) just to draw some buttons on a screen. And all that effort for 1/10th of the UI flexibility that HTML/CSS/JS affords you.
In other words, electron is OK because the alternatives suck. That doesn't mean it's good but it's the best of a terrible bunch.
learning a second layout system just for desktop apps is going to be a bit of a hurdle for gaining dev enthusiasm.
That's a huge cultural problem right there. Some devs seem to think that their software is a special masterpiece (obviously, since it's made by an ensemble of rockstars), and therefore it'll run alone on users' computers. But that's nearly never the case; even the least technical users run many applications at the same time. Unless you're writing a fullscreen videogame, your software should never assume it has 100% of machine's resources for itself, and these days, even most videogames shouldn't.
(Or, in other words, tragedy of the commons.)