While I'm not 100% on Qt's history, some quick Googling finds references that suggest moc was around in the Qt2 days, which was 1999, which was before even C++03 was a thing. So it's mostly a historical relic, now hidden away as much as possible by things like automoc in cmake.

Also, FWIW, moc-ng is based on libclang, which looks to be vaguely in the general direction of what you're getting at: https://woboq.com/blog/moc-with-clang.html

it does provide some limited reflection which is in my opinion the biggest missing feature in C++. (and no, I dont want to use macros for this)