Almost the only people that benefit from transfer passengers through the UK are the airport operators; the passengers do not leave the airport and therefore add almost nothing to the wider economy.
Until that is you take a few steps backwards and see the slightly wider picture. Most transfer passengers are transiting the UK because either one or both of the relevant sectors are on UK carriers. That is UK busineses, who employ UK nationals and all of whom do contribute to the wider UK economy. Indeed many of the readers of these forums are directly involved in these busineses and are directly affected. Lufthansa, Air France, Swiss, Olympic, KLM, Iberia,
et al do not hub through Heathrow, Gatwick, or any other UK airport, so their transist business will route through other European hubs.
I honestly see no reason not to encourage passengers from the regions of the UK to transfer through Schiphol, Frankfurt or Dubai rather than Heathrow. It's not a matter of dogma but merely of economic and environmental sense.
Anywhere as long as it is nowhere near the particular back yard you chose to plant yourself in then ? How does delivering customers into the central hubs of our competitors make economic sense? Unless you mean it makes great economic sense to them, in which case I expect they would be salivating at the thought.
The trouble with this sort of tortured logic, is that if you actually succeed in killing the golden goose, the contraction has a knock on effect on general demand in an area. Still, I expect your ire at dinner parties could then turn to the incompetent government that has driven down the value of your house that is no longer in an area of such high demand.