Agree with your opinion; but it's a fact that stand alone rakes have better chances to get LHBfied, than those with RSA.
12685/86, 12623/24, 16527/28 and now 12673/74 got LHB rakes as they needed maximum 2 rakes. Else priority lies with weekly service like 16311/12, which operates with single rake.
MAS - MAQ Mail has RSA with West Coast & Malabar; so it'll require minimum 4 LHB rakes for its upgradation. Feel the present policy is not in favor of 1 Mail LHBfication.