A survival horror about dinosaurs can't exist because an action game that includes fantasy dinosaur-like creatures does?
That sounds like saying you wouldn't have space for Resident Evil because of Fallout, and those arguably have more overlap than Dino Crisis and Monster Hunter in their settings.
I mean I could be wrong, I haven't played Dino Crisis (though I intend to at some point), but from what I know and have heard it's not that close to Monster Hunter. People have been looking for AAA Dino horror-type stuff for ages. They wouldn't bring up Dino Crisis instead of Monster Hunter in those discussions if they filled the same niche.