I am pretty sure there is a commonly used exploit with your autonomous report system that has not been fixed ever since the endorsement system was created.
I have done some experimentation and I have discovered that indeed if 2 or more people send false reports to another player, it will automatically lower their endorsement level. I even tested with being reported for verbal abuse when the player didn’t even use the text or voice chat but the player still lost an endorsement level for verbal abuse.
This bug means that players are encouraged to play together for the wrong reasons, when they are angry, they will report spam someone with false reports and that person (regardless of their innocence) will be punished.
It is ridiculous that a bug (where you can lose an endorsement level for being falsely reported even when you played your best and refused to communicate to avoid false flags) like this exists.
In case blizzard ignores this post as I expect they will if it doesn’t get popular, know that if you don’t like another player for some reason, you can always report them for anything (even if they didn’t do it) and they will lose an endorsement, level. Apparently this experimentally confirmed feature is intentional.