Unfortunately I think this is a naive take, because it's focused on technical superiority. That's only part of the story.

Companies partner with massive vendors like Oracle and jump through their hoops to remain in support contracts because it enables them to defer some liability and satisfy various regulatory checklists.

Think about a database instability scenario for an online retailer, and consider if you'd rather be the CTO who is to blame for self-hosting, or the CTO who can defer blame onward to the vendor. It's an unfortunate reality in many "enterprise" environments.