As someone that has recently taken an infant and and family CPR class for my son who started solid foods a few months ago, this is pretty similar to how they teach it today and I'm pretty sure it would have the same effect. You can't perform a heimlich on a baby or very small child for a variety of reasons. This method or something similar to it is both safer and more effective, since it lets gravity help dislodge the food.

Paramedic here, this is still half of how it's done for choking in small children and babies. Five back blows, flip, five chest thrusts.

I....don't get it. This is an old way to help a child that has something stuck in their throat. I mean, the heimlich maneuver was first described in 1974, so I guess this WAS in fact the best technique at the time. Keeping someone from suffocating is kind of important, and this seems like something you can do fast and easy (at least with a relatively small person).

That method is still mostly recommended, though mostly for younger children/babies. The Heimlich maneuver is difficult to perform on a small body. You either over squeeze, and cause harm, or are too tentative, and so not helping.

With babies, you hold them lying on your forearm, facing downwards, and slap (open handed) hard. I've only seen it used once, but it worked perfectly then.