Qt has been around for a while and though it gained traction Electron is far outpacing it. It seems that there is no ASP.NET Core since it was borne out of an actual use case with ASP.NET.
Again, kudos to the author and it seems like a great technical feat, but to my knowledge what matters is adoption rate.
You're acting like the whole desktop app industry has moved to implementing desktop apps in HTML with Electron.
Fortunately for users this assertion is false, given how shitty most Electron apps are usability and performance wise (VSCode being the only exception).
As for Qt, web devs have C++ allergy, hence why the company behind Qt came up with QML. exactly to fight against this trend.
To me this makes sense. Web developers will typically have a handle on HTML, CSS, JavaScript, Python, PHP, SQL, NodeJS. Some will even be good at most of these. There's design patterns on most of these that are significantly different. The context change from one language to another exacts a toll, which I imagine why Node found a niche in the first place. Electron seems to be finding another.