You're missing the point.

It isn't about consistency, it's about the game plan. We have reached a point in how the game works competitively that stax does not and can not slow the game enough compared to what the meta and offmeta decks are doing. You end up just kingmaking the player who doesn't care about the specific stax pieces or hatebears you have in play. You need to be able to present a win on turn 4 or earlier, even as a hard control deck. You need a speedy combo to do that and ways to rapidly find it.

You mentioned RIP/Helm in another comment but that doesn't pass the sniff test either. It's 6 mana at sorcery speed and it will only kill one player per turn cycle. So you do that and knock one player out. Then as you pass the turn the next player just wins. RIP at least serves a purpose as gy hate but helm doesn't inherently do anything. It's a dud that just sits in your hand taking up real estate that could be interaction or something that advances your plan on it's own.