As someone that administrates a small handful of workstations and a server or two, I just don't get what these tools buy me. It seems that usually installing an application via one of these methods has negative externalities (e.g. some things not working out of box, like access to user file, or ability to play audio), or most often the applications simply don't work at all.
If snaps were able to work properly out of the box, they could be good if they reduce the work for the packagers. That said, I've burned enough of my time trying to debug broken snaps that I won't entertain ever using them again.
I guess if it works for someone else's use case though, that's nice. However it sure seems pretty grubby to install a snap when the user clearly intended to install an DEB package via aptitude.
I will say, I've had very positive experiences with AppImage. I haven't really dug into the technical details of how these different approaches work yet, since I haven't had any reason to, but every AppImage I've wanted to use has always worked perfectly.