[pointyhatuk]

Well your database is a black box technically speaking. It's very hard to scale it horizontally and it is very expensive to scale it vertically as time goes on.

Logic suggests that you should keep as much processing functionality outside something which can't be scaled cheaply or easily and push it to cheaper front end servers.

On this basis, anything which implies more work than collecting and shifting the data over the wire shouldn't really be in the database. Parsing / processing JSON is one of those things that's going to eat CPU/memory.

Fundamentally there's nothing wrong with storing JSON inside the database and processing it externally, but processing it inside the database is a big risk.

I've seen the same thing over the years with XML in the database and more recently people adding CLR code to SQL Server stored procedures.