Yeah I think it's very situational. Like an arena allocator is going to give you a tremendous bump in allocation performance since you just allocate once and replace memory every frame - to give the gaming industry example.
An arena allocator isn't going to be the underpinning of the new operator.
It could be!
I think it’s the other way around. Instead of redefining operator new() to allocate from an arena, user allocates memory from the arena and then constructs instance there using placement new.