Yeaaah, no.

I've been told, and this source is certainly reliable because I know him and he wouldn't bs me, that wind direction depends on the nearest island(s) and where their centre or highest point (I don't recall the exact details) is. It was clearly implied the information's origin was some official source, too.

The discussion took place in a voice chat months and months ago, so I don't have an exact quote. But what he said made sense (certainly a lot more than this theory), and nothing I've observed in-game contradicts it.
In fact, I always know what the wind direction is going to be at locations I sail in/past often -- and no, it does not make any difference whether said locations have a portal.

It really is as simple as being dependent on the world's geography.
Not anything a player does or has. That would not even make any sense.