I think this is a slightly different point from the other responses, but this not true: if I am seriously optimizing something I need ssh access to the same chip.

I don't run my production profiles on my laptop - why would I expect to compare how my i5 or i7 chip on a thermally limited MBP to how my 64 core server performs?

It's convenient for debugging to have the same instruction set (for some people, who run locally), but for profiling it doesn't matter at all.