C’s problem is that my “way it is done” is different from yours.
Your friend uses Docker. My friend uses Apt (and hopes the libraries he wants are in there). Someone else compiles by hand and uses pkgconfig. Or CMake files. Or VC++ referenced projects. Or XCode projects. Or autotools. Or hand written make files. Or ninja. And so on.
Universal tooling only has value when it’s universal. Adding yet another contender to the mess doesn’t really help unless it becomes a standard.
Docker is orthogonal to the other tools you mentioned. You use apt or pkgconfig or autotools or hand rolled configuration inside of Docker (ignoring cross-platform issues for brevity).
Your friend uses Docker. My friend uses Apt (and hopes the libraries he wants are in there). Someone else compiles by hand and uses pkgconfig. Or CMake files. Or VC++ referenced projects. Or XCode projects. Or autotools. Or hand written make files. Or ninja. And so on.
Universal tooling only has value when it’s universal. Adding yet another contender to the mess doesn’t really help unless it becomes a standard.