I think these comparisons are silly because they are trying to find some blanket universal rule. What works most of the time might not work in your specific case.
https://en.wikipedia.org/wiki/No_free_lunch_in_search_and_op...
https://en.wikipedia.org/wiki/No_free_lunch_in_search_and_op...
Says who? The author goes into detail about what exactly they were measuring. The last two headings are "When Flat Designs Can Work" and "Limitations of the Study." Can you clarify exactly what you found "significantly flawed"? I don't get what you're trying to say by your wikipedia link.
> What works most of the time might not work in your specific case.
So what? Is it not worth knowing what works most of the time and under what assumptions?
I feel like Flat Design works for a specific use case, though you'll have to imagine one because I don't know of any, but it has been applied universally.
Many interfaces I encounter nowadays seem like every interaction is an Easter Egg, where clicking / tapping around randomly is World's Best Practice for feature discovery.