nothing really prevents you from defining global allocator in Zig
and having explicit allocator in standard library is actually a good thing, cause it's quite a common case in game development to use arena allocators which are being freed once per frame - so you don't really need to reinvent your data structures in Zig
I do have some concerns about Zig because it also introduces some friction for correctness sake like requiring to always use all variables, explicit casts everywhere - I want some compiler toggle to disable all of that and focus on problem but unfortunately it's not there
I am playing with Zig now and haven't really formed my opinion about game development specifically but I like it a lot so far