Clean build environments for CICD workflows, especially if you're building/deploying many separate projects and repos. Managing Macs as standalone build machines is still a huge headache in 2025.
One clever and cool thing Tart actually does that sort of relates to this discussion is that it uses the OCI format for distributing OS images!
(It's also worth noting that Tart is proprietary. Some users might prefer something that's either open-source, built-in, or both.)