No, even if the benchmarks are private, it's still an issue. Because you can overfit to the benchmark by trying X random variations of the model, and picking the one that performs best on the benchmark
It's similar to how I can pass any multiple-choice exam if you let me keep attempting it and tell me my overall score at the end of each attempt - even if you don't tell me which answers were right/wrong
Now I’m wondering what the most efficient algorithm to obtain a mark of 100% in the least amount of attempts. Guessing one question per attempt seems inefficient. Perhaps guessing the whole exam as option A. Then submitting the whole exam as option B. And so on, at the start, could give you a count of how many As are correct. Then maybe some sort of binary sort through the rest of the options? You could submit the first 1/2 as A and the second 1/2 as B. Etc. hmmmm
Maybe there should be some rate limiting on it then? I.e., once a month you can benchmark your model. Of course you can submit under different names, but how many company names can someone realistically come up with and register?
It's similar to how I can pass any multiple-choice exam if you let me keep attempting it and tell me my overall score at the end of each attempt - even if you don't tell me which answers were right/wrong