> Ok, I admit that a lot of papers compare only against other metaheuristics, but only in cases where it is already accepted that those other metaheuristics far out-perform weaker methods.

Those methods are invariably other evolutionary methods, and benchmarks are cherry-picked to show only encouraging results under the convenient guise of the "no free lunch" theorem. That' pretty much the norm, such as the repetitive recipe for inventing a metaheuristic algorithm of a) coming up with a clever nature-inspired metaphor with a catchy name, b) put together an algorithm that is arguably inspired on the metaphor, c) come up with a benchmark that arguably portrays the algorithm as being any improvement, even if only on a fortuitous corner case.