I don't know what the 5th highest reviewed title of all time that was made available on a popular platform selling well tells me about the state of AAA as a whole to be honest. One data point, for a game considered a masterpiece of the last generation (so the decade), doesn't say a whole lot.

The Avengers was a large AAA game from the world's most popular media franchise and it recently tanked. "That should tell you everything you need to know..."

In general people don't care whether a game is a "AAA" or "indie" when they buy it, they look at reviews and whether their friends are playing it.

There are good AAA games and bad AAA games. The good ones do very well, the bad ones don't do as well. If we move the goalposts to say that the high-grossing/well-reviewed AAA games don't count then of course we're going to end up with a skewed picture of what the market looks like.

Because the Avengers game wasn't very good. On the other hand the recent Guardians of the Galaxy game sold much better and has received overwhelmingly positive reviews.