It was not made public why Victoria was fired. Neither of the parties are talking about it, so generally it's unknown.

The /r/iama mods were not upset that she was fired. They were upset that there was no transition plan in place.

> it seems like there was a lot of finger pointing before anyone knew what was actually happening

There was finger pointing because nobody knew what was happening. Functions that Victoria was performing fell through and — according to the /r/iama mods — jeopardized the functioning of the AMAs that week.