As another person stated, this results in more "please report 9x (so and so) they did (such and such a thing they didn't do or exaggerated)" being spammed for 10+ minutes in a game just because players want to trigger something.
The beauty of the system right now is it is literally impossible to game reports to ensure a punishment is applied (or a manual review is conducted). One report triggers an automatic review, and there is no published method (and likely not any at all) for definitively triggering a manual review. This both means that nobody can game the system to ensure someone gets punished (by getting a lot of people to report) and also ensures that players have absolutely no reason to say "report x" in game (which is negative and tilting to the player x who is being targeted).
I think the other thing that needs reminding is that there's definitely a lot of players out there who are going to report for negative attitude or intentional feeding when, to be quite frank, they're just mad at the player for whatever reason. The player may have said nothing in chat (or very little, all positive) but they get 9 reports because their score was 0/14 at the end of the game. The automated system can easily filter those out - but if it were to trigger a manual review it would take human-hours which don't exist to ensure that they were invalid. A human will always take more time to review it than the computer will.