It does not get you banned. It may get you squelched temporarily if it is a chat report, but not banned. That is not usually used in RBGS though.
The most common claim is that a person feels they were falsely reported AFK and got suspended for it. Claim it is automated. Only to have the Forum Support Agents check the logs and yeah…it takes multiple games worth of AFK reports to get an account punished and those have to be verified.
I have been an MVP for almost 10 years. Mostly CS/TS. I most certainly don’t have to agree with or “suck up” to Blizzard. Nor is anything I am saying false (or at least never intentionally). CS/TS folks spend their time explaining things to other players and helping them. You don’t have to like what is said, but that does not make it untrue.
Here - Vrak covers most of the Battleground questions related to the penalty system and reports.