I don’t know what’s your source, but this is wrong. In HotS the protoss could expand faster than right now, specially in PvP and PvT, due to the nexus/pylons overcharge being an effective deterrent to early game attacks.
Gate expand was the go-to opener in PvT/PvP, with zealot-mothership pokes possibly being game if successfully transformed in pylon rushes. Now the protoss can still time a poke to kill the CC building SCV with their very first zealot, and add a quick stalker to that ; but the zealot stalker poke was out since WoL, so there’s nothing new out there.
If anything the deletion of the MSC forced protoss to 2 gates expand more often in PvP, and to cyber expand more in PvT (I say more, but that build was nearly non existent before MSC’s removal).
So yeah, the protoss can use his CB to poke at your natural quicker than you could with a matching build ; but that’s nothing new under the sun.
What favors Z is the requirement to expand faster than in HotS, since they are the most mobile of the 3 races. But they also took a big hit to their larvae mechanics, which somehow compensates. Both having nothing to do with the 12 workers start.
Take a look at this :
https://youtu.be/SAo3QwnPruc
Tell me what he does in the first 39s.
Well, aside than getting a few SCVs and spamming like a crazy, the answer is nothing. Those 40s are dead time to a player, and boring as hell to a viewer.
Compare it to now, where we rally the first worker to build the depot/pylon in the very first second.
All what the 12 workers start did was get rid of that dead time.
And, looking back at those game, I think that’s the best decision DK ever took for the game. 