More Unicorn Poop
This sounded like a pissing match between some big egos. In the end Amazon still uses Oracle for some of its functions. Most of us don't have the luxury of unlimited resources including capital and labor to make the transition. We can't find the skills to have people run open source databases and AWS "services" and if we do we certainly can't keep them.
I'd rather lock in to a company that has a proven track record, a huge labor pool, and enterprise class support versus a company that tells you to just build it. As the old saying goes "If it ain't broke..."