The ability to come back is awesome, although I have never had a reason to use it.

For a distro hopper like yourself it would actually make like so much easier! Because of how subvolumes work - you can have every distro in a separate subvolume. They can share the home subvolume if you like, or not. You can have upgrades with a failsafe of sorts for the likes of Ubuntu, which, in my limited personal experience, have never ever been without issues.

Having a server subvolume to run portage in and then snapshotting it to a desktop one, applying desktop config saves some time on recompiling the big friends like gcc and llvm.

I did not understand the point of BTRFS at first as well, especially since it was slower than ext4. But since having started using it I’ve found that there are now scenarios that were not possible before or were incredibly complicated. Like read-only root, incremental backups over the network (yes, rsync exists, but this feels cleaner)