I disagree, actually. I have found microbenchmarks to be very informative to understand why a language is fast in some cases and slow in others.

It's not only the actual benchmark numbers though. Its understanding the code that reaches those numbers: Can Julia do explicit SIMD? How awkward is that in one language or the other? Are there idiosyncratic bottlenecks? Bad design decisions that needs to be worked around in one language but not the other? And so on.