I am actually finding the mult-city search function surprisingly useful.

For instance, EDI to DXB; the simple BA search will say that the cheapest flight at the moment is about £3.5k. However, if you use the multi-city search for EDI-DOH-DXB return you get options from £2.3k on BA codeshares on the direct EDI-DOH QR flight or EDI-LHR-DOH (admittedly less convenient), with QR connections onward to DXB (and a visit to the Al-Safwa lounge if you choose well).