If you're working on a nice code base that has a very clean boundary across teams and infrastructures, have the arena boundary follow that principle and the sys

If you're working on a nice code base that has a very clean boundary across teams and infrastructures, have the arena boundary follow that principle and the system has relatively straightforward lifetime and ownership, then yes. Obviously this is not true for so-called "large scale software systems". Have you tried to bounce objects across arenas thanks to all the teams that wanted to "optimize" and "simplify" their memory allocation? Good luck with debugging that.