I think it is useful because our field is woefully inept at anything resembling backtracking, and it's having concrete detrimental effects all over the field by, for example, increasing mountains of bloat eating up hardware improvements.

> SPA's have really nice performance characteristics. [..] A good SPA should offer the same capabilities too

The problem is that not even large teams without any obvious lack of resources are also unable to prevent sluggishness from creeping in to SPAs. So I guess there's a theoretical SPA and a de facto one.

> But it wouldn't be anywhere near as capable, as interesting, and as loved.

Capable sure, if you're creating Google Earth style apps. But when you start using vague and extremely subjective adjectives like "interesting" and "loved" it should be a signal that something's off here.