there are beach routes and there are beach routes, routes such as Mykonos, santorini etc the more niche destinations and ones harder to reach from the regions were always LHR routes even pre covid. The AGP, ALC, FAO etc types are easier from the regions so connections through London is much less attractive, sure BA offer a club product unlike the regions but for. 2 1/2 / 3 hour to somewhere like AGP, connecting rather than direct is not very attractive,also pre covid BA didn’t need feed onto the LGW beach routes as they were filled with Gatwick joiners