Here’s my take on it:
Many players have been AFKing or playing passively in AV. Those players were being reported across many games and Blizzard has a process for investigating AFK reports in AV. They look at the account in question and how many games that player had zero or close to zero damage/healing. If they notice a pattern, they flag the account for suspension.
After people started appealing their suspensions, Blizzard realized their criteria for suspending people in this wave included too many people who were actually defending objectives and happened to have a lot of games where they incidentally did zero or close to zero damage and healing. Such is the nature of a BG like AV, where a conflict of strategies between opposing teams could leave players defending objectives with no one to fight. Blizzard realized their error after reviewing appeals and decided to remove the suspension on many accounts.
What sounds more reasonable, this explanation or the ludicrous claim that Blizzard has given every player GM banning powers with extra steps. One person earlier claimed that it only takes 5 reports to automatically ban someone. Does that mean that each individual account has 20% of a GM’s power to ban people?
Also, Orlyia basically confirmed some of what I was theorizing just now: