If this became popular enough, wouldn't GUI frameworks just optimize for these 7 use cases? And then the benchmark wouldn't be so useful.
That's not exactly the case in GUI frameworks - where the different axes of evaluation (ex. expressiveness etc) would require lots of changes to logic and API of the framework (as this is not about mere performance).
And even if this did happen, optimizing for those 7 use cases would make them (a) better than what they are now, (b) better for 7 very common cases, which cover most of everything.