i think the reason is more that arena's let you manage lifetimes in groups instead of pointer chasing. if you have to manually manage memory, it's eaiser to manage a small number of arena objects instead of a large number of individual objects.

eg https://www.dgtlgrove.com/p/untangling-lifetimes-the-arena-a...

that being said, it's even easier to not manage any lifetimes at all :)

although i suppose some will say that you still manage lifetimes in rust, you just have full support from the compiler to make sure you do it right. that seems better to me than relying on simplification to ensure you don't make mistakes.