In video games, you need to solve problems. Usually, you will use whatever tools your character has to solve these problems. In Scribblenauts, you use Einstein. Or a Kraken. Or anything else in the universe.
If you still need convincing, here's a story from someone who played the demo.
So listen to this story. I was in the early levels; I didn't quite have an idea of how ridiculously in-depth the database was. I was summoning things like ladders, glasses of water, rayguns, what have you. But I reached a level with zombie robots, and the zombie robots kept killing me. Rayguns didn't work, a torch didn't work, a pickaxe didn't work. In my frustration, I wrote in "Time Machine". And one popped up. A smile dawned on my face. I hopped in, and the option was given to me to either travel to the past or the future. I chose past. When I hopped out, there were dinosaurs walking around. I clicked one, and realized I could RIDE THEM. So I hopped on a DINOSAUR, traveled back to the present, and stomped the **** out of robot zombies. Did you just read that sentence? Did you really? I ****ING TRAVELED THROUGH TIME AND JUMPED ON A DINOSAUR AND USED IT TO KILL ****ING ROBOT ZOMBIES. This game is unbelievable. Impossible. There's nothing you can't do.
One thing I don't get about this game, what stops you from just typing in "god" (or something similar) every level and winning? Obviously that would miss the whole point of the game, I was just wondering.