People who actually need (or simply assume they need..)ACD capability regardless of the total number of channels should build their own and be sure to have the house wiring capable of delivering the juice and meeting local codes.
The vast majority (99% or more) of applications don't need such capability. Manufacturers are doing the right thing not implementing gigantic 150 lbs AVRs or amps just to keep a few people happy and force the added costs, real estate, and probably reinforced support structure, to 99% of the users who don't have such requirements.