Your claim was that it never happened, this was just a single well known example of it happening.
At that point, Valve says a team of people will investigate those anomalies, and, if they determine that something fishy is afoot, they’ll “mark the time period it encompasses and notify the developer.” If Valve finds that coordinated review bombing has indeed occurred, any reviews posted during that time period won’t count toward the game’s review score.
Also it isn't fully automatic. Valve claims that people are involved 'evaluating it', and the result of the evaluation was that reviews were not counted.