IIRC it wasn't just the ABI break that was a problem, it was the fact that they wanted to build on systems that didn't have a C++11-compliant compiler available yet.
In 2012 that was reasonable. In 2024 that would be unreasonable, but they are not stuck on C++03 in 2024. C++17 today with serious plans to force upgrade to C++20 in the near future is a reasonable place to be today.