How to fetch and create documents while using Server Component in NextJs?

I was following this tutorial by @Dennis Ivy . One thing I didn't understand was why we are creating a new session using createSessionClient before fetching the documents. Why can't we directly fetch it like this:

 const { documents: orders, total } = await databases.listDocuments(
            process.env.NEXT_PUBLIC_DATABASE_ID,
            process.env.NEXT_PUBLIC_COLLECTION_ORDERS
        );

Second question I have is why we are creating an API route to fetch the data from Appwrite DB when we can directly fetch it from the server component to avoid an extra API call? (That's one of the benefits of using a server component.)

Tutorial Link: https://www.youtube.com/watch?v=ENnG7GusuO4
Source Code: https://github.com/divanov11/Nextjs-Appwrite-Auth-SSR/blob/main/src/app/api/orders/route.js

Any help is appreciated!

How to fetch and create documents while using Server Component in NextJs?