and perhaps also because their core engine (warning: it's highly speculative) does not require an internal core clock.
Turn Based + countdown timers + flags may be seen as a sufficient way to get the job done.
The reason I am mentionning this off-topic point is that this would explain the quite chaotic way the characters (or your multiplayer friends) enter the combat mode, especially if a dialog is involved. The transition between the game modes seems to be managed with spatial parameters, no timing consideration. Depending on the conditions, you may have a character able to run kilometers long before the first cycle is over or be locked.
More generally, how/when/where a clock/timer is used is not just a cosmetic matter.