Crazy Personal Headcanons

[SilverArrow20XX]

Don't worry, every other game in the series, including FFXIV, instead disproves this theory by going interdimensional. The main thread showing this one is Gilgamesh constantly going in and out of--oh, look at that--the Interdimensional Rift.

Time and space are dimensions. You use the Rift between dimensions to bypass normal space. Kinda like Shadesmar of the Cosmere.
A place far enough removed in time and space might as well be another dimension.
The Rift is used to warp, time travel, and travel to parallel planes.

The After Years also disproves it, because it implies that the Creator actually destroyed all those other worlds.

The boss cameos in TAY are the same as the cameos in XIV and any other game, they're just references, not the exact same characters. Except Gilgamesh, of course.

It only implies that The Creator seeded those worlds and seemingly intends to destroy them at some point. Whether it's already been done or not isn't specified. I like to think he was stopped from doing that when he was defeated.

It's just a more fun way to view the series to me.
Handwaving explicit connections as "just cameos" to shut it down doesn't make much sense to me.
Pupu is another connection. There's also the "word of God" on VII and X sharing a universe, so why not all of them?

I also firmly hold that every single dumb crossover event is fully canon. Come at me.