It's a cathartic, but not particularly productive vent.
Yes, there are stupid lines of time.sleep(1) written in some tests and codebases. But also, there are test setUp() methods which do expensive work per-test, so that the runtime grew too fast with the number of tests. There are situations where there was a smarter algorithm and the original author said "fuck it" and did the N^2 one. There are container-oriented workflows that take a long time to spin up in order to run the same tests. There are stupid DNS resolution timeouts because you didn't realize that the third-party library you used would try to connect to an API which is not reachable in your test environment... And the list goes on...
I feel like it's the "easy way out" to create some boogeyman, the stupid engineer who writes slow, shitty code. I think it's far more likely that these issues come about because a capable person wrote software under one set of assumptions, and then the assumptions changed, and now the code is slow because the assumptions were violated. There's no bad guy here, just people doing their best.