I’m aware the state you were talking includes state of all threads.

When you combine several sequences of state transitions (one sequence per thread), you don’t get another sequence of state transitions. When two CPU cores perform two state transitions at the same time, you typically cannot determine whichever of those transitions happened first.

We might have different definitions what’s sequence. I mean this: https://en.wikipedia.org/wiki/Sequence As you see, global order is required for bunch of elements (in this case, state transitions) to form a sequence. And in concurrent and especially parallel programming, there’s no global order for those transitions. Hence, those transitions don’t form a sequence.