That was my question. I always though pushing was faster, so I'm glad im not the only one. I'd love to see firm numbers to prove that though.
I think it does seem counter intuitive, because of the way you seem to go even faster if you get the draft from a distance behind in a lengthy leap frog. But I'm thinking the idea is that if you do this, you're losing speed at times even though you're gaining speed at times, and it evens out. So pushing winds up being overall consistently faster. (At least that's my hypothesis to explain it.)
Thing is, I'm on the fence with believing that bump drafting is actually faster than leap frogging with slower cars. (By slower cars, I mean for example, we do ovals in the Low HP League using kei cars tuned to 400pp - which is not very fast on ovals. Certainly not like a NASCAR stock car.) And on a few occasions it definitely seemed like leap-frogging was getting me & the other car up faster gaining on the leader, than when we were bump drafting. This of course could have had something to do with the relative speeds of our cars, and which of us was able to bump draft the other.
By able, that's the other thing that comes into play with it not being say a 1-make race... if you have various models in an oval draft battle... I'm leery about bump drafting with certain other cars that look awfully skittery & unstable. I worry I could lose my draft partner to a spin from even a slight bump draft tap just a tiny bit off-kilter. So if the other car is more unstable than mine, I'll sooner encourage them to bump draft me, than to get behind them to tailgate.
Take for instance you're in a shuffle race, and your draft partner is in a Yellow Bird.

Or you're in the Low HP League and your draft partner is in a weight reduced Honda Beat & already showing signs of sporting damage.
Bottom line of course... You can't bump draft someone else over the finish line and win yourself.

Clearly, draft passing is the way to go if you actually want to get ahead of another car before the finish. haha.
My usual strategy, if I can manage it, is to be in 3rd place behind 2 cars closely drafting each other, and then leap up using both cars just in the nick of time.

It's worked on many many occasions. haha.

But it has to be timed carefully... and that's a lot to do with luck.