I don't know the details since I'm mainly a windows dev, but when porting to linux, TBB has always been a huge pain in the ass since it's a suddenly additionally required dependency by gcc. Using C++ and std::thread.
Also clang, and in general parallel algorithms aren't available outside of platforms not supported by TBB.
C++26 will get another similar dependency, because BLAS algorithms are going to be added, but apparently the expectation is to build on top of C/Fortran BLAS battle tested implementations.
Using pthread in C, for example, TBB is not required.
Not sure about C11 threads, but I have always thought that GLIBC just uses pthread under the hood.