Isolation via XPC is a good idea, but it's also a good chunk of overhead. It's a lot of added effort and room for error in the case of one-man indie apps/side p

Isolation via XPC is a good idea, but it's also a good chunk of overhead. It's a lot of added effort and room for error in the case of one-man indie apps/side projects (which a lot of mac apps are) for barely visible benefit and it's potentially problematic for scenarios requiring high rates of throughput. For examples where (at least to my knowledge) the macOS sandbox isn't flexible enough, consider trying to write a reasonably capable file manager or terminal that works within the sandbox's bounds. Or even a simple music player capable of opening playlist files which could point to music files sitting anywhere – not just the user's home directory or the boot volume but anywhere on the local file system.