All of these sounds like surmountable engineering challenges that one should have weighed when evaluating the data layer. "You don't own your data" is downrigh

All of these sounds like surmountable engineering challenges that one should have weighed when evaluating the data layer. "You don't own your data" is downright false -- you own it, you just don't host it. But do you ever really host it these days? Unless you're running it on your own hardware in your own facilities, probably not. So what the author should say is "migrating is expensive because we chose to build on top of a SaaS product using a proprietary API and we're surprised by this because we didn't plan any further than a single 3 week sprint".