It’s almost a classic argument.
A blog is like a house you built yourself from the ground up.
Using a Facebook Page is like renting a shop on a popular street.
If you build the blog, you have to make it interesting enough for people to stop by. You can do what you want.
If you lease, it’s already built & people are already there ready to buy. You just need to personalise and leverage it.
Like most things, you probably want to lease first to get a feel for it, then buy later once you know what you’re doing.