Dubai is slot contained, and they fly to plenty of other slot contained airports.
As far as I'm aware, London to Dubai alone has seven daily A380 flights. More generally, Emirates have gone for a single daily A380 flight instead of more frequent flights to many destinations.
It's just a hub at an arbitrary (for travelers) location.
People aren't actually going to Dubai. DXB is an extreme of course, but trasnfer passengers represents a huge part of the activity for many hubs: 30% of passengers at LHR are in transfer, and more than 50% at ATL!
They're well positioned as a hub between Europe/USA and Asia+Australia. Emirates as the stopover is literally in the middle (also counts for their ME airline cousins, as they are all next to each other).
Plus with current flight lengths, you need a stopover somewhere. That is changing, though.. with Perth-London direct opening soon. That's a long time to be on 1 plane though. And it's only a little shorter (1-2h) than going via DXB.
