You can always hypothesise success without Facebook because if it didn't exist, people would find alternatives.
But it does exist, and in any town or city there are dozens of people running microbusinesses in competitive niches that rely on word of mouth and recommendation which is largely sustained through Facebook comments, "I'll message you!" and tagging in posts and photos.
Anyone in hustle culture — odd job/handymen, mobile hairdressers/beauticians/nail technicians, day workers, gardeners, plumbers, event photographers; Facebook is unfortunately crucial to keeping the doors open.
All of these people could have websites, but people don't browse websites. They could run ads in newspapers, but people don't look at those. And google is dead for stuff like this, listings and trade directories are not much good either.
At the lowest level of freelance income, Facebook is basically indispensible because it is the only social network with a regional basis and solid local group mechanisms, and because your both your customers and competitors are there. It probably sustains tens of millions of such workers.
This is where the tension lies. For sure I wish Facebook would shrink and that the web was healthier and people would understand the damage it can do, but "just don't use it" is not advice that works for millions of people.
It is Facebook that needs to change, through slow attrition of engagement with bait content and scam ads.