Who really knows. Adelaide may just been overcome by the occasion.Adelaide smashed Richmond at home that year. You may believe what you want, but they are the facts.
But the side with familiarity with the ground and not travelling does have a little more of their routine available to deal with that occasion.
MCG is almost certainly an advantage to Vic sides, and especially those who play there regularly (North or St Kilda, if either make a GF before the expansion of the sun, likely won't have that part of the advantage). The size of that advantage is hard to really tell.
Probably not huge, and arguably a little less than during the regular season due to the crowd being made up more of neutrals and corporates, but it has to be there.