If you read contemporary reporting about anti-Muslim riots in Myanmar https://www.reuters.com/article/world/special-report-buddhis... you may learn that there were Buddhist monks traveling the country, giving sermons to crowds of thousands of people, telling them to treat Muslims as enemies, and stickers being used to visibly signal alignment with the movement.
Careless People is a story about Facebook from inside Facebook, so of course it adopts the viewpoint that Facebook's moderation decisions are very important, but ultimately they were a sideshow to what was playing out on the ground. This goes double for military attacks on Rohingya villages, which can hardly be explained as spontaneous reactions to some Facebook post.
In any case, Facebook moderators literate in Burmese would've known to use the right font, whereas for Facebook moderators trying to deal with a language they can't even read, the font choice would be the least of their problems.
Facebook's direct culpability in the ethnic cleansing in Myanmar had already been well-known and thoroughly reported on many years before Careless People.
The internet and the real world don't exist in separate vacuums. Internet communication and amplification of hate speech helped create an environment where hateful sermons were planned and popularized, and vice-versa.
Facebook pages and posts espousing these viewpoints (using sensationalized or completely fictional justifications) were then amplified by the algorithm. The amplification reached people that were not otherwise inclined to participate, but were convinced through information they received online.
You can't have one without the other. Influence is driven through both in-person physical events/marketing and online platforms. Categorizing the online influence as a "sideshow" completely misinterprets how important online communities have become in radicalization. "Reach" is a key social media metric for a reason.