The broader argument is that pausing a thread is a misuse of them. Also, you need to consider that the qt thread abstraction may not be a true system level thread, but instead a pseudo-thread that supports the common threading api and behaviour (to some extent).
As for pause/yield/etc as in coroutines...seems like it's a 20 year full circle back to the era of cooperative multi-tasking, when the favored model has clearly become preemptive MT.
Seems to me that the hint about how qt threads exist would be whether
std::this_thread::sleep_for() works as expected, or does it introduce side-effects?