Do vex always exist? If they are part robot, part organic, and utilize the same shared space then they must. For the most part we think the only thing they want is ones and zeros, but they can't survive without the organic radiolaria...so they can't be solely 1-0, they must be organic.
It's just something to think about, question the logic of this game.
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Kind of, they're still in the process of weaving themselves in to the universe. You can tell by how descendants look( they look rusted and overused, like they can't make vessels anymore ), also when Osiris stated they had many timelines that failed. The space is definitely shared within their important areas, like VoG and the infinite forest( Saint-14 quest line ). If needed they can pull all timelines to one place.