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.
The type of building is irrelavant to the problem. Anything that works for apartment complexes works just as well for a single family house. It’s always the land underneath that’s the issue.
And at the ond of the day any solution that include getting rid of landlords comes down to the government seizing “unused” or “inappropriately used” land more aggresively. Something that just doesn’t sit right with most people.