Your second point is why paying for such services makes a real difference.
Companies like storj.io, backblaze, or any other cloud storage/backup provider provide a service for a fee with (not really) clear usage rules. If you're encrypting your stuff before it goes to the cloud, you're pretty safe from scanning, and if you have a contract for a given space and bandwidth, the worst you'll probably run into is overage fees.
To tack on to this, with an example that is easier to grasp - I have my own cloud, comprised of machines at my house, my friends, and family.
Those machines provide backup storage for each other, over the internet (using an encrypted connection).
If I were to charge people for storage, I'd be little different than any other cloud storage provider (at the most basic level).