Comment by adrian_b

For now, in server applications the ARM CPUs can win when the workloads are not computationally intensive, i.e. they consist mostly in data transfers and searches, for example in Web servers, database servers, storage servers, networking appliances, etc.

There still are applications where ISA matters, like technical/scientific computing, where the performance can be dominated by array operations or operations with big numbers. For such workloads the x86 CPUs with AVX-512 can provide a performance per watt and per dollar that cannot be reached by the current ARM-based CPUs.