I've read this twice but...?
I have an MSc in Computer Science specialising in databases, but I don't immediately understand what this article is saying.
I can see that sometimes you will have trouble scaling your database servers unless perhaps you pay a lot of money for sophistcated versions of RDBMSs. However it's not obvious how the simpler file stores on eg AWS overcome the same problems. That really needs to be explained.
Some people like ORM approaches. Some people no doubt still write COBOL programs that happily talk to sequential files. Databases however are still the preferred choice in the majority of situations, so any Cloud service needs to provide RDBMS functionality.