that receives hype
If Titanic was some low budget indy film, that would be a fair complaint.
But when it's one of the biggest films of all time.
Constantly referenced, in the popular zeitgeist for years. Changed movie going for years. If this was Crank 2, sure I would be perfectly ok with someone not knowing. But it's not.
This isn't about having a photographic memory for every scene and plot point. (Although if you think you need that to remember the media you've watched. Yikes, hate to be you)
At a certain point it changes from "I haven't watched this so I don't know" to "I am deliberately going out of my way to pretend to not know anything about this"
That's being a contrarian, that's being culturally blind, that's trying to be a hipster and proud of it.