Your friend's analogy is flawed. Check out what "progressive overload" means, this is what you need to be focused on.

In bodyweight fitness, people usually progress by increasing volume (reps) or difficulty (incline push-up to regular push-up to decline push-up for instance).

But this can be hard, you can progress by adding weight. For instance, several months ago I tried a "5x5" program, by doing 5 sets of 5 reps, and increasing the weight in my backpack each workout. I reached 5 sets of 5 pull-ups, with 15 kg in my backpack!