I think I just had a realization. Perhaps my frustration is my fault, in that I was trying to look at snappy as a truly universal cross-distribution software packaging system. That seemed like the goal to me.
Now, however, after reading some of the comments on External repositories, I think I see my mistake and misunderstanding. Snappy isn’t the universal cross-distribution software packaging system I was looking for. It’s the cross-distribution end-user-focused software app store I wasn’t looking for.
I’m approaching this from the IT professional and system administration perspective, and trying to solve enterprise system and software distribution/management/update problems. I thought I could make Snappy fit into that, but I now suspect that I was wrong, and that Snappy doesn’t actually care about my problems (at least not if they in any way conflict with the goals of being an end-user focused app store (with an excessively strictly enforced update ideology)). Perhaps I’m not the only one to make this mistake?
I would never put Snappy on any server I’m responsible for because the current design is broken from an enterprise system administration perspective (at least, it is to me). However, from a user desktop or laptop perspective, Snappy’s forced updates are maybe (slightly) less obnoxious.
I still fundamentally disagree with the update stance (see previous comment about not being able to think of any single platform that is so determined to force its views on updates on people), but since it seems intended for a different use-case than mine, I’ll just move along and focus on alternatives that fit professional systems engineers better.