I used to advocate the weighted pushups idea myself, until I realized an important thing, which I'll ask you: what is the limiting factor in the continued increase in the weight, and does the bench press suffer from this limitation?
The two limiting factors are your ability to stabilize your torso in a safe position, and your ability to load the exercise safely. Though the bench press is a full body exercise, it's easier to stabilize the torso, and loading the exercise is far simpler.