As a company, you'll want full control of your online appearance, which you don't have on platforms. Often you may not be able to comply with regulations on other platforms, like having to have a T&C-Page. And often it's not much cheaper to maintain a platform-page than a website. You still need (marketing-)personell to handle updates, news etc.
I think the draw is that the upfront cost is super low on facebook.
Versus whatever it is your contractor dude or dudette wants to charge.
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