JSONB columns are incredibly useful if you have data that doesn't fit well into a strict relational schema. And they are very powerful in terms of query ability in Postgres, but still quite far from a conventional relational schema.

Queries that act on the insides of a JSONB column are much harder to write than the equivalent conventional queries. They are also much, much slower in certain cases as the DB has to read the entire JSONB blob in many cases, and because they don't have proper statistics. The performance can range from slightly slower to completely pathological query plans that take ages.

I'm a big fan of JSONB in Postgres, but it is no replacement for a relational schema, there are far too many problems you inflict on yourself if you try to use it like that.

Access, but not constrain or type-check.

And it's just harder to use, I'm with it being generally a 'mistake' (in the 'you will regret this later' sense) - it's better than text, but I'm in the camp of as much structure as possible ('you will thank yourself later').

As others have mentioned, it definitely does have downsides when it comes to writing queries and especially when using frameworks/libraries to interface with the db.

But for the right job, JSONB columns are awesome!

What’s a real world example where you would choose to index the JSON as you said rather than putting them into the fields/schema.