It's good enough for the folks who choose to do it that way. Many of them do things that are quite "serious"... Databases, kafka, the lmax disruptor, and reams of performance critical proprietary code have been and continue to be written in java. It's not low effort, you have to be careful, get intimate with the garbage collector, and spend a lot of time profiling. It's a totally reasonable choice to make if your team has that expertise, you're already a java shop, etc. I no longer make the choice to use java for new code. I prefer rust. But neither choice is correct or incorrect.

> Databases, kafka, the lmax disruptor, and reams of performance critical proprietary code have been and continue to be written in java.

those have low bar of performance, also they mostly became popular because of investments from Java hype, and rust didn't exist or had weak ecosystem at that time.