That's what you get with Qt absent the moc (meta object compiler).

Moreover, there is still a host of reasons why Qt is a painful developer experience (even though it is probably the best cross platform native option). For example, even if you solve the editor problem, you can't reliably use C++ templates, and Qt has its own strings, lists, hashmaps, concurrency mechanisms, memory model, etc. And even if it were just C++, C++ itself is a pretty poor experience compared to other languages on the market these days.

So Qt might be the best thing on the market today, but it's not hard to imagine much better alternatives. For example, browser support for native system things that would render electron obsolete (especially as WASM matures) or perhaps Flutter as its desktop story matures. Or maybe even a mature intermediate GUI toolkit in a modern language.