Unless the disc is loose. Finally, we know the reason for it. j/kI don't expect to change anyone's mind, but...
A sealed game is simply a piece of plastic in a shelf.
It may have a game you might like, it may have a full color manual.
You will never see it or know it if you don't break a completely arbitrary wrapping of plastic and actually open it.
I'm with you though. I don't find much appeal in a sealed collection, unless you're looking at it as an investment. Even then, it can take long enough to pay off, surely there are better ways to invest money. It can be neat to have some sealed stuff around, and I can see why people might want to go for it, but to me a lot the appeal of collecting games is to build a library of things I can play.
I would always think the same thing about seeing older games on eBay still sealed. If for some reason I were to buy this, would I really know if there was a game in there? Nah. And if I never planned to open it or sell it, would it really matter? Also no. When buying brand new, like from LRG, it's probably a safe enough assumption that the cart/disc is in there though.
With the modern game situation, it could make sense. Digital versions of a lot of these games can be pretty cheap on sale, so there are cost effective options for people that want to keep a sealed copy and still play.