I feel like internet slapfights would be a lot more peaceful. Hypothetically trolls won't get a rise out of people in the same way as OTL because they'll go "You're entitled to your opinion no matter how fucking stupid." Exposure to strange ideologies from all spectrums might also stop the polarization of politics OTL.
Or encourage polarisation even further, depending on the country.
How many people will genuinely be tolerant, and how many will have a "more diverse than thou" attitude is yet to be seen.
I mean aside from the whole mandatory riots thing (which I can deal with), this sounds like a nice world. I don't see any downsides to it compared to OTL.
Yet.
Besides, diversitarianism works differently in different countries. We have the liberal California brand, which seems to be "embrace the multiculturalism".
Then, we have the middle-of-the-road Anglo-American brand, of "diverse but separate", where immigrants are encouraged to come; however, not only are they discouraged from assimilating, they have to live in dedicated neighbourhoods.
Then there's the authoritarian Russian brand, which, from what little we can glean, is "every ethnicity is precious, and cannot be allowed to mix lest they become diluted. Oh, and all societists should be phlogisticated, except that wouldn't be properly diversitarian - in that case, only phlogisticate
most of the societists and contain the rest".
Who knows what everyone else's diversitarianism is like.