I used to do this too, but I think it's especially due to the fact Argentine pizza typically looks like this:
Or at least, it should look like that.
That pic was taken at a 1930s pizza parlor where I used to eat every day, because it was right next to my office. A slice of that and some coke was pure happiness. When I was on the night shift, one of the (cheapskate) Italians would ask the pizzeria for leftover slices before closing time, lol. We'd all have a slice after midnight and then fall asleep.
Here in Chile they do that gringo thin pizza with the toasty cheese that doesn't get your hands dirty, and I stopped eating it with a knife and fork.