Load testing can be hard. Wrk works for me for the most part but it's not ideal for complex flows (say e-commerce trying to simulate a real browse and checkout

Load testing can be hard. Wrk works for me for the most part but it's not ideal for complex flows (say e-commerce trying to simulate a real browse and checkout complete with typeahead search). However the smarter apps can have problems too. I've pinned all available cores on fairly beefy machines because they are gunzipping bodies (behaving more like a real browser). If you are at a scale where you need really good testing I recommend that you think of wrk results as comparable to a unit test and something like jmeter as comparable to an integration test. It's not worth the effort for most companies but where I work we serve a decent amount of traffic and downtime costs 6 figures per minute so good performance engineering and good business overlap.