Yeah, but SotC was released twice before. The Last Guardian wasn't a re-release or remake.
I think another example we can look at is Ratchet and Clank, that also had a remaster on PS3, and was remade for PS4.
And the remake was reported to be the biggest opener in the franchise. I think SOTC has a lot more of dormant audience that has heard a lot about the game but has never played it, and the new shiny graphics might be what pushes them to finally give it a go.