[JosephLark]

> something available in C++11 (that's C++ released in 2011)

Nit: The standard was finalized in 2011 - August 2011 to be more specific, so quite late in the year. Full compliance in various compilers was not achieved for quite some time after that - MSVC being quite problematic in that regard.

Major projects - esp. those compiled on multiple systems across several compilers, like Firefox - absolutely could not just go ahead and start using C++11 in 2011.

I was really into native development around that time, and C++11 was the first time I was exposed to the complexities and gotchas around standardization vs. implementation. I've stopped paying as much attention since, but I believe C++14 fared much better.