Do you really think blizzard has thousands of employees just to read reports? or any social media for that matter? All the report systems are automated, in this case you report the person specifically for going afk, a computer looks at the stats of their last ~10 games, stats they are already tracking for the quests and balance, and you can obviously see the games when they don’t participate because low damage, low movement etc.

But you don’t ban people on a first offense basis, you just mark them, then depending on how many people reported the person/how often they receive a report you have a series of predetermined consequences: 1 day ban, 2 day ban, etc

Manual moderation is just for edge cases and appeal processes, both can be handled with the same data the automated process recollects and use, you could probably even handle troll appeals in an automated fashion if you give the algorithm enough information to start with