Running benchmarks is not only useful but necessary. It's a point where planning meets the real world. Private clusters are also routinely benchmarked, often as

Running benchmarks is not only useful but necessary. It's a point where planning meets the real world. Private clusters are also routinely benchmarked, often as part of validation. In the end if someone just tells you their supercomputer "would" be in the TOP500, they just tell you that it is definitely not in the TOP500. There might be good reasons for that, but still, it's like claiming that you would win Olympic gold if only you'd bother to participate.