Garbage collection is certainly a part of it, but really, it's about programming with a deterministic runtime. Controlling memory budgets and doing things described in this talk is possible in an environment where the programmer has control, but instrumenting a blackbox runtime to identify performance bottlenecks and pain-points can be a huge endeavor. Other languages optimize understandability of the programming semantics (what is this algorithm doing) but do very little to aid in expressing runtime semantics (how will this algorithm execute on the machine).
[1] http://plexchat.com [2] https://www.jetbrains.com/cpp-today-oreilly/books/Cplusplus_...