I agree with the general sentiment just wanted to point out that "my schema is my app layer" has some valid use-cases. At my current job we deal with highly complex schemas (modelling insurance contracts). Correctness is paramount but at the same time you need flexibility in terms of change over time. Defining these schemas at the DB level would be painful, a bit like writing web apps in assembly. Languages like Haskell (which we use) help here with their rich and expressive typing capabilities, so we can model these complex domains expressively and use the DB only for persistence. Admittedly it does have downsides, like having to write your own migration layer, but for this use-case the benefits outweigh the pains.

PS.: We do use Postgres though ;) as it has 1st class json support and at the same time we have the luxury of using its relational capabilities where needed (think of a hybrid model).