I don’t see this “exception” any different than other exception for critical systems (ie example of having snaps in a car or any kind of critical machinery or [in my case] breaking the network for a few seconds to minutes because of snap updates.) Some places this might be a danger of high cost (data or outage damage) or potentially other serious harm. I think some of these places are just not (yet) ready for snap packages - or maybe just not for snap packages from the store as manual installs are not triggering any updates.
As a sidenote, trying to understand the concept of the tracks, so I can potentially make a difference between critical new snap’s or just minor (ie help text) fixes. Anyone knows a snap which is a good example and has this implemented?