No, the use in Anaconda is perfectly legitimate. Docker aside, I use it for automatic snapshots. That's a fairly useful and unique feature that you can't have in any other legit way (not counting zfs, and btrfs is deprecated). There is also the yum-snapshot plugin that relies on it. It's not even that complicated. Just throw a few gigs at metadata and forget about extensions. If I have 2TB hard drives, I don't care if you use 16 G for metadata, which is the max.

LVM snapshots are really slow though.

That's the whole selling point of thinp (at least for root and home). They are supposed to be faster than regular snapshots.