Some probably only saw it during their format education, and it's most likely been taught like C with classes and/or they had to use for stupid things.
There are also many forms of C++, there is your "old and regular" C++, game dev C++, there is modern C++, then there is "I only know C, but sure I can write C++" C++.
Pulling dependencies is not as simple as `npm i boost`.
Communities are small, segmented and not welcoming to newbies.
Absolute madness with build tools. I've never worked with CMake myself until last year, and I haven't so frustrated.
As for how many applications using C++ that's not really an argument — C++ was literally the only choice for many of them at that time.