I think for some it is just easier - they don't need to get their nephew to build a janky website, or cut into their profit by having someone build a decent one.
The older blokes in particular probably aren't worried or even aware of the issues with Facebook. For them, it's just a place to share pics of their grandkids visiting and boomer memes etc.
Even with the younger crowd - when I move, which is every few years, I often find new hairdressers on Facebook; few bother with a website. They're already on there and it's a great way to show their work to a wide range of potential clients.
Almost no one is going to a website every few weeks to check out updates from their favourite artisans, but they will scroll through a social feed and often interact with the posts.