"All Eldrazi are pieces of one of the titans. No titan, no 1/1." We did have Vestige of Emrakul in Battle for Zendikar after Emrakul had already headed off on her way to Innistrad.

Titans aren’t planeswalkers, so they don’t move from plane to plane the same. Vestige of Emrakul was the last vestige of Emrakul left on Zendikar as it was moving slowly to Innistrad.

The flavor texts of multiple cards, some of which were cited in the comments of the original ask, clearly indicate that Eldrazi stragglers do exist. Vestige of Emrakul and the UMA printing of Ulamog's Crusher provide decently indisputable evidence of this. As someone who very much disliked the way Eldrazi were handled in BFZ-OGW and SOI-EMN, I am glad to hear the focus is away from them, but excluding them entirely seems like a clear mistake. They are part of the world's identity now.

In spite of what characters of the world might think, Eldrazi spawns are extensions of the titans. If they are dead (or locked away in a moon), there can’t be any. I believe both flavor text comes at a time where people falsely thought they were dead.