I lived through the C++11 transition (which was the only actually significant improvement C++ has ever had), and as much as GCC 4.6 was enticing, it really wasn't a burden to keep supporting GCC 4.4 in stable software. Only for ground-breaking development (which takes long enough to stabilize that stable distros will have the new GCC) is it worth starting to use the new features unconditionally.

Now, C++ does have a much better source-level compatibility story than most languages (e.g. `#if ... #define constexpr /* compiler too old */`), but that just means that newer languages have no excuse for refusing to learn from its successes.