And does anyone actually believe this? Because I certainly don't.
The 1% is players who are consistently highly toxic. The ones who actually get punished for their actions.
Most of the toxic players that you encounter in your games don't get punished for it, so they don't appear in that statistic.
Next time you encounter a really toxic player, look at their profile after the game and check how much honour they have - they often have hundreds of points. Bear in mind that punishment resets all honours to zero.
The problem is that you have to be extremely toxic, and consistently so, before you get punished, so most people don't have any fear of punishment for their actions. This also means that it generally takes a long time between toxicity and punishment, further making people unafraid of bad behaviour.
If the systems that they had in place would detect negative behaviour immediately, and apply some kind of punishment (even if only a light one for a first offence), it might help to get people to understand that their behaviour is not acceptable.