Hi,
As you say power gain is related to matching, since matching networks are difficult to implement in a IC(transmission lines are huge-although recently for 60GHz designs they are starting to implement them integrated-, L,T,Pi matching networks needs passives(inductors) that are also very large in terms of area) once you deliver the maximum power to the LNA using an off-chip matching then you don't usually try to maximize power transfer between blocks, you just  make a voltage amplification.
Hope it helps,