But it makes the data skewed, and brings question to its validity.

Most of us remember the days when the majority of the groups decided to switch to h264 (and .mkv to contain it natively). It showed exactly how many morons there were among us who watched anime and had no clue what a codec ever was.

When I stared checking some of Y's claims (which are true, though mostly through hackjobs and 3rd party plugins) I'd say the overwhelming majority of forum threads I found through search were from 2005-2006. Most of the complaints were during the switchover. Mostly by people who had never heard of a codec pack, and just played everything in Windows Media Player.

.avi was introduced in '92. Not exactly the explosion of internet communication. It's no surprise there aren't any complaints, especially considering it is windows native as Kraco pointed out.