Though everything works in practice, it seems like this ECS organization in C++ is encumbered with all of these issues, some as simple as issues with new entities occlusion with currently looping iterators. I admire what they did, but it just seems so unpure and not pristine.

Is it just the nature of the area of development..gaming? Or is it just because C++ is pretty much defacto for perf, and no large company is going to rock the boat?