This rep system is absolutely joke. u can even get banned for abusive chat given the fact u dont talk to any1 . I have it perma disabled in-game options . 
Its pretty bad. In theory you could get banned by just being reported once in a while (because they just add up and never get removed against your account) regardless of whether the report is justified or not. This is not unique to HoTS btw - people have tested the system in WoW by mass reporting people, triggering suspensions.
As a funny/sad sidenote, at one ARAM game (and I know it was it because it was the only HoTS game I did in the week), three of us reported one another for being afk when in reality only one of the people stopped playing by roaming around the map. Result = I get 24h suspension and receive two separate emails saying that action was taken against people I reported. So if this is to be believed, the three of us cross-reporting each other triggered automated action regardless of the reasons or reality on whats happened.
One could literally write a book on how Blizzard not only struggles to handle toxicity but by not providing players with any tools to avoid interacting such players, they practically borderline let it cultivate over the years.