Except that's not true. Although these companies do encrypt your data, the vast majority of these services keep a copy of your encryption key, which they can secretly use at any time to look at all of your data.
Sure, these companies likely want to do the right thing for reputational reasons, but the same could be said for Equifax and CapitalOne and Experian and hundreds of other finance and healthcare companies that each spend hundreds of millions of dollars every year on their computer systems. Just taking a look at data theft throughout the industry and we have to ask ourselves: WHY should anyone have confidence in a backup service that has full access to all of my data?
To put the nail in the coffin, all these services have legalese that makes it clear that they are not responsible for any data theft caused by their failures. They simply are not willing to take on the liability of protecting your data.
The solution, of course, is simple: Companies must not deal with data that they cannot risk losing. For the Cloud Backup business, that includes customer encryption keys.
Personally, I cannot trust these services with my data. There is too big of a risk for me if they do the wrong thing.
The fact that industry publications gloss over these very real security risks is strong evidence of their poor advice.