There are just more flights to the places that i go to from Heathrow.
I think you missed my point entirely, I was saying fly locally to another major hub the equivalent of LHR. e.g. BHX -> AMS -> HKG, vs LHR -> HKG there are just as many flights from other major international hubs as there are LHR. The local flight means no driving/parking over a longer distance and bigger costs.
My next flight to Japan is actually 1 stop, in Helsinki. Direct flight cost pretty much the same but I booked a 1 stop in Prem Economy and only takes 2hrs longer. Plus mine will land before i can check into the hotel (about 11am) whereas the direct flights land in the evening, meaning i lose half a day.
You see this is where I would have booked local, with one stop then direct. You are travelling to LHR then taking a stop which makes it an even longer journey. Obviously if you don't have a local airport nearby then it make the decision harder.