There is a very big difference between what particular environments offer in theory (yes, you can write object pools in Java and many high-performance projects use them) and the situation in practice (there are people who spend a large chunk of their professional careers doing JVM tuning).

Idiomatic Rust avoids the situations which require JVM tuning experts. You can write a Rust service, put it into production and tail latency is very likely not going to be a problem at all.

Now you may decide that needing the occasional services of a JVM tuning expert is better overall than ownership concerns being pervasive throughout a codebase, depending on the specifics. But do accept that the trade-off exists.