alt Hacker NewsOne word.
Headers.
That's just the start. The C++ build system and package managers are the stuff if nightmares. Modern languages are significantly easier to use.
Don't get me wrong, if you offer a job with a 200k base salary and give me 6 months to learn C++ I'll do it. But I won't enjoy it, and I definitely won't do it as a hobby.
If you use an existing template (and are willing to use scons) GDExtension doesn't really have the standard build problems of rigging everything up with CMake/etc in my experience. The template is set up to handle the "set up the build" problem for you. Still have the header problem though cannot deny that one.