why would the average user need cloud-only?
Because, as has been repeatedly demonstrated in these parts, some people are digital hoarders. What they actually access, routinely, is a very small part of all the junk they drag around with them, and there's really no point in having it locally.
But, even ignoring all that, with any cloud storage (at least the paid stuff) you have the option of truly cloud-only, streaming down to local temporary storage on-demand, or always present locally and always syncing to the cloud. This is why cloud storage is just so damned convenient, particularly for residential and very small business clients, who are notoriously bad about backing up anything. Your computer or its local storage can be completely destroyed and you lose nothing. You just log in to your cloud-based storage when you fire up the replacement and, bingo!, it all just appears again automagically. This is what has sold me on cloud storage, where even though the terms of service have the CYA that we don't guarantee your data won't disappear, in practice with all the redundancy and professional data center management, they do. Better backup than most people who don't use cloud storage will ever be able to create locally, and definitely if the backups are all in the same physical location as the source. One fire or flood and its
all gone.
And I've said it before and I'll say it again, anyone, and I do mean anyone, who is using cloud-based storage and knows it has to know that an account, with login credentials, is how they connect to it. If someone says to me, "But I don't have a Microsoft/Dropbox/Google account and I've never had a password!," when they say something like, "My stuff was on OneDrive," the response is, "Oh, yes, you do and you now need to help me figure out what that is if you didn't keep those credentials. You have to keep all account credentials for email, cloud storage, etc., just like you do for your online banking, credit card, etc."