Sorry for taking so long to get to this. If it helps, I am writing this from Switzerland and eating some local cheese while writing this up.

A few things are needed to make a cheese wheel that large. First you need a steady supply of milk cows — you need hundreds of litres of milk — and land to pasture them in. In places like Gruyères this is readily available. You also need a steady supply of fuel. To make many cheeses, you heat milk with rennet and a souring agent around 50°C. To do this regularly, that's a good bit of firewood, so you're not going to be making such cheeses in the Savannah (which anyway is hot enough that you're only going to manage something like feta at best).

So that enables big wheels. But why would we want to do that other than to show off?

One good reason, at least for Swiss varieties such as Emmenthal which is brine (salt) cured, is that having such a large volume of cheese means that the curing process takes longer, which in turn lets the _Propionibacterium freudenreichii_ bacteria — which are characteristic of Swiss-style cheeses such as Emmental and Dutch cheeses like Edam — to propagate. If the cheese were smaller then the salt would seep through the wheel quicker in the curing process and kill off the _P. freudenreichii_, which is what gives many Swiss varieties of cheese its large bubbles. The huge wheels thus offer up a benefit for the growth of necessary bacteria.

With Emmental and other Swiss varieties there's also the added benefit that the larger the wheel, the better and more gradual the cooling process is for the curd. As mentioned above, you make cheese by heating milk to around 50°C, but then once it starts to curdle, you need to bring it back down to a normal temperature to press and salt, but if you do it too abruptly, it can cool unevenly and anyway more importantly the bacteria only become active after the heating has completed, so if it cools too quickly you won't get good fermentation of the lactose in the curd.

Those are the main reasons Alpine cheeses have such large wheels. Now as processing is better and more technologically advanced, all of these necessary conditions can much more easily be controlled for, so smaller cheeses can be made quite consistently. Edam is actually the cheese variety in those little red-wax-covered Babybel cheeses, and those are obviously tiny. They also make Emmental, with yellow wax, and also tiny. Hooray progress?