[Spivak]

I'm not entirely sure how true that actually rings because it's true by definition in some sense but having tables just be loose collection of typed nullable columns sans natural (maybe compound) primary keys is a very different experience from the kind of thing you expect. It's a schema in the way @dataclass is a schema and just ends up being a place to put stuff. It leads to very very few joins being necessary, natural keys map well to most problem domains, and foreign key constraints feel almost unnecessary since your real data is the key it's really hard to "lose" relationships.

[BoiledCabbage]

It feels to me like you're mixing the terms schema and relations/joins.

You can have a schema on a table without any foreign keys or relations. But in the above you seems to use those concepts interchangeably.

Taking OPs comments directly about schemas, it seems true to me.