But you are comparing things that really aren't comparable.

A ticket from Luanda to Dubai, and a ticket from Luanda to London are entirely different "products". Even if, for both (when purchased from Emirates) you end up travelling on some of the same services.

Each city pair is its own "market", and the demand for travel on each city pair is tracked and monitored completely separately. Because flying Emirates means you would always have to fly via Dubai, of course it seems "logical" to the passenger to compare prices against a Dubai trip. But that doesn't make much logical sense.

Emirates will track the numbers of people buying tickets for, say, Luanda to Dubai, and as the number of such tickets increases, the price will tend to increase for later customers who enquire about the cost of such a ticket. However, the plane that travels from Luanda to Dubai is not merely filled by passengers who wish to end their journey at Dubai - there will also be passengers travelling on this flight who will wish to change to flights to other destinations, near and far. Each of these "markets" is tracked separately, and just because there is a high demand for Luanda-Dubai tickets, for instance, does not necessarily mean that this "high demand" must be fed through to passengers with other destinations.

Luanda is an expensive city; so is Dubai; I expect that fares for the direct flight between these two cities are always relatively high (in, say, comparison to flights from other African cities of comparable distance). However, while Emirates might already have sold 50 tickets for Luanda to Dubai to be operated by a particular flight, meaning that the very cheapest tickets advertised on the Luanda-Dubai market are all gone, they may not yet have sold any ticket for, say, Luanda-Athens that would require a seat on that flight, so there could still be rock-bottom cheap seats available on this already-busy plane for customers wanting to fly from Luanda-Athens.

And this is not just applicable to Emirates. Or to just one route.

If you look at Cathay Pacific's current offers from the Netherlands, it is cheaper to fly to Beijing (€620), Shanghai (€620), Bangkok (€655), Tokyo (€670), Manila (€685), Jakarta (€645) or Hanoi (€735) than it is to just fly direct to Hong Kong (€777) - despite the fact that, for all of these destinations, all passengers will be travelling on the same plane as, and then further, than the passengers who paid the most to travel just to Hong Kong.

Airline prices are not bound completely by distance, and by number of sectors. In fact, when an airline can offer a direct service, they can generally afford to charge a premium for this - that is why tickets on EK to Dubai from most outstations will actually be more expensive than tickets to some other destinations that require a transfer (and the same goes for most airlines). Each city-pair is unique, and subject to its own pricing. You are familiar, I am sure, that a flight from City A to City B and back is seldom the same price as a flight in reverse - from City B to City A and back. In each market, the airline will track prices, and charge as much as the market can bear.