A list like the IMDb one will always be skewered towards more recent releases. Most registered and voting there are young and are rating new movies. They wouldn't likely be voting on films from the 60's, 70's or 80's, for instance, and the site didn't exist in those decades. It doesn't surprise me much at all that 13% of that list are recent releases. If you remove the votes from 13-20 year olds I think you'll have a different list. Though, again, votes will still be heavily skewed toward new titles. Take the title at the top of the list...80% of the votes are in the 18-29 age group. I would guess the bulk of that section is the 18-20...films before 1980 (before they were born!), that were the "worst ever" aren't likely on DVD and they've never seen them.
Nope...it's not shocking at all.
edit to add...minors are not the fairest 'voters' anyways. I just looked again at the #1 film's page and noted someone posted "I've never seen it, but I voted 1 (of 10 stars) anyways!" Three others replied they just did the same...so there you go...four of the votes (at least) putting it among the worst ever are invalid. I wouldn't imagine someone would take the time to do the same for movies over previous decades.