Why does Sequelize adapter require DB connection info instead of existing instance?

Hello 🙂
Quick question, I'm new to Casbin, trying to set it up with Node.JS & MySQL.
I saw that it has a Sequelize adapter in order to persist on the database.
My question is, it seems like the adapter asks for DB connection info (username, host, port, etc') and doesn't take an existing Sequelize instance.
If that's the case, and it has to create a connection on its own, why would I even care that it's Sequelize under the hood? I might be missing something, but from my perspective, it might as well could just be called "casbin-mysql-adapter"? should it matter to me in any way, other than maybe installing one less package for it to work?
Would love for a clarification about the matter, thanks!