Someone should edit that page quickly 
j/k
i think ‘most effective tactics available’ might be a backronym. ie it was called ‘meta’ before, then someone came up with the ‘most effective tactics available’ acronym.
as to what the ‘beyond’ part is, let’s have a look at gaming loops (this is largely opinion):
the primary game loop of age of empires is: queue units, give commands to available units (ie things you to every second/tactics)
secondary game loop of age of empries is: make decision on which units to focus on/upgrade, where to place castles/TCs, map control, unit compositions etc (things you do every minute/strategy)
tertiary game loop:
which civs to play, what overall strategy to go for (ie go FC/fishboom/maa into archers etc. this would be meta)
meta gaming would then mean to anticipate your opponent’s/opponents’ strategy/civ picks and counter pick
and the logic by which different strategies counter each other, eg: on arabia maa+towers punishes full wall FC etc
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