Arena allocators are not some grand new concept. They're already commonly used in C++ in the places it makes sense to use them. Which is really not that many places, it's a fast but rather niche optimization. There's not a whole lot of scenarios where lots of temporary memory is needed for one well defined scope.

Video games are large and have lots of state and lots of threads. Zig's lack of ownership here with fully manual memory management is overall a poor fit.