The point is that you are the mercy of the snap publisher, and as the sysadmin, you cannot prevent the software from updating. Whether you should or not do that is a different debate.
You'd expect that publishers follow the same process, that a stable channel means it's really stable, whereas version breaking changes really end up in per version channel. Ideally you have the latest/{stable,beta,candidate,edge} which follows the latest version of the software, and eg. v1/{stable,beta,candidate,edge}, v2/{stable,beta,candidate,edge}, v3/{stable,beta,candidate,edge} for individual version. A simple concept but surprisingly hard to follow.
Maybe the publishers are really lazy and don't care about the users or the maintenance cost of keeping n versions around is just too high, in which case it's up to the users to make their effort worth it.
The point is that people want to be able to disable automatic updates, even minor ones, and that's not possible.
edit: I can see how my previous comment could have been confusing. To clear it up, I was trying to say that a workaround for the forced updates would be for vendors to publish a "single version channel". So version 1.2.3 would be a dedicated channel, with no updates ever. Version 1.2.4 would be a separate channel, with only that single version. This would of course be impractical, for both the vendor and the user.
