> Alas, many developers in enterprise are rusted onto a record-keeping CRUD model and struggle to think in columns rather than rows. The idea of inserting an entity id into a “published” table, instead of setting a boolean “published” field to true, doesn’t always come naturally. Yet once you realise how readily polymorphic this is, you may start wanting to use such approaches to data for everything

I don't really understand what's Polymorphic about this, or even beneficial. It seems like everytime I've had a boolean column in a long-standing application, it eventually needed to turn into something else