A significant problem with traffic replay in a few cases I've considered in the past is HTTP POSTs and usage of headers. For most, logging that extra info is not realistic and rules out traffic replay as a possibility for simulating realistic load.

Quite often, everyone one the team will already know which endpoint(s) are slow or unscalable. In that case, it is possible to set up a much less realistic load test in order to generate some flame charts of the problematic area. It can be more pragmatic than having to maintain what is essentially a new integration test suite as the author mentions.