That's not meaningless at all, it's a great metric! If the "cost per correctly-solved benchmark task" is infinity, you know not to use the model.
I want a model that generates commit messages fast. Currently I have to wait up to a minute or two. That model doesn’t need to score very highly on SWE benchmarks, just highly enough that it can write out a good enough message in a few seconds. If you tested it on ${current top tier benchmark} you’d think it’s way too costly when in fact it’s the best tradeoff.
(see their follow-up reply: "The cheapest-per-benchmark-task model would be useless to me if it cannot do the task I need.")
In either case, you need the right benchmark for the right task