While my farts can also be trusted, the few times I doubted them I still went to the toilet just to be sure. It never turned out to be necessary but I’d rather take 20 seconds to go to the toilet and be safe than having to deal with the aftermath of a misjudgement.
A lot of users are also from poorer countries that lack the means to create their own web infrastructure. Using Facebook to run your business account is easier, cheaper, and more reliable than most alternatives there. Phone carriers and ISP often also have “free”-data for certain social media platforms. You get 1GB+1GB for Facebook/IG/YT/Some Game. So you are stuck in this loop where everything reinforces itself to use Facebook.