Perhaps this is what people who don't play games think games are like. You must have had that moment where you're playing a game and there's a locked wooden door in front of you and an axe in your inventory, and your friend says, "Why don't you just smash the door down with the axe?" And you have to respond, "Look, just shut up, you don't know what you're talking about, OK?"
In Scribblenauts, if it seems like it should be possible, it's likely going to be possible. In fact, what Scribblenauts is capable of is so astonishing, so utterly complete in its collection of everything ever in the universe, it seems like it can't possibly be real.
Surely in a level which sets me the challenge of crossing main character Maxwell across some shark-infested water to reach the target Starite (the star shapes that represent your constant goal), it's not realistic that I can type in that I want an Ichthyosaurus, and then see whether it can beat the shark in a fight. Nor does it seem reasonable that I could tap in "PEGASUS", jump on the winged horse's back and fly safely over. It starts to get a little silly when I ask for a teleporter, step in, and find myself in an alien laboratory.