My understanding of Historic Gates is that they win by getting 9 different Gates into play and then activating Maze's End. There is a secondary plan of direct beatdown with big creatures (Primeval Titan, sometimes Gatebreaker Ram, and Zacama/Atraxa/Ulamog as in the example decklist), but it is secondary. In particular, since these creatures are vulnerable to removal and the deck plays few threats, opponent is odds-on to be able to answer them. The Gates deck can still win with them, but the Maze's End plan is the primary route to victory.
Given that, why would these decks run Yorion as a companion? Yorion seems like it just decreases the odds of drawing the key cards in the deck (Primeval Titan and Circuitous Route especially; Gates Ablaze too against aggressive decks). I can see that Yorion works exceptionally well with Thragtusk, but that doesn't seem worth it. Blinking Primeval Titan & Elvish Rejuvenator is of course good, but also does not seem like it's worth it - untapping with Primeval Titan is almost a win with Maze's End anyway, so one cannot count on blinking it. As for Elvish Rejverator, by the time one has the mana to cast Yorion, that extra 1 land of ramp should no longer be a big deal.
Comparatively, my understanding of other Yorion decks is that they are composed of nearly interchangeable, generically good cards (e.g. 4-color Yorion) or have enough ETB abilities that the Yorion blink trigger is highly relevant (e.g. Yorion Death & Taxes).