This theory needs working but here are a few key points to it:
The pirate legends are ghosts, just like the ones we see in the tall tales that lead us to the sea of the damned
To get to the sea of thieves you have to go through the shroud, similar to the one in the sea of the damned. And you have to have a map to get there, which might be something you need to believe in the Sea of Thieves then after travelling through the shroud you arrive at the place you hoped to get to. Similar to how the Sea of the damned can make your fantasies come to life, as seen in the monkey island tall tale.
Those are my few ideas, definitely not much and barely any at all. But it's a start and feel free to add on to this theory. This was something that just came to my mind in a matter of minutes.
Thank you
