Spot on Hippo with
“Ask yourself how many passengers on EK’s MAN-DXB services terminate at DXB and you have your answer as to why it wouldn’t work for BA.”
This is the main point. Emirates use smaller UK cities to ‘scoop up’ their foreign pax to connect through Dubai, BA scoop up the same way with many non-hub cities around europe to connect through LHR.
BA’s old Manchester to Islamabad route had to be cut for this exact reason.