Benchmarks are always fishy, you need to look at things that you'd use the model for in the real world. From that point of view, the SOTA for open models is quite behind.
If benchmarks are fishy, it seems their bias would be to produce better scores than expected for proprietary models, since they have more incentives to game the benchmarks.
No... benchmarks are not always "fishy." That is just a defense people use when they have nothing else to point to. I already said the benchmarks aren't perfect, but they are much better than claiming vibes are a more objective way to look at things. Yes, you should test for your individual use case, which is a benchmark.
As I said, I have been following this stuff closely for many years now. My opinion is not informed just by looking at a single chart, but by a lot of experience. The chart is less fishy than blanket statements about the closed models somehow being way better than the benchmarks show.