I mean, they're also talking about using the same table multiple times - aliases aren't just useful, they're required in that case so the engine knows which one

I mean, they're also talking about using the same table multiple times - aliases aren't just useful, they're required in that case so the engine knows which one you mean when using a column from one of them. Best guess without actually seeing these queries, whoever wrote them is using bad aliases (like "foo1", "foo2" and so on) instead of something more reasonable.