People in Iran or China don't rely on Facebook and Instagram. Before Facebook penetrated Europe in ~2010, each local market was dominated by copycat services like StudiVZ or Hyves, which then vanished within 2 years. When the US floated the idea of banning TikTok, some people felt compelled to download Chinese social media apps.
If a country was to ban Facebook from operating in their country, people would be on an alternative 2 weeks after. There are reasons why a Facebook ban would be hard to enact, but dependence on the product is not one of them
I think you’re not aware how deeply engrained WhatsApp and instagram are in Brasil.
I think dependence is definitely a problem because everyone would get mad at you for having to switch. Sure in the long run it wouldn’t be an issue but immediately you will lose some voters