Admittedly, yes. This is the massive appeal of Mongo et al., or just JSON[B] columns in an RDBMS.

Unfortunately, at a very deep level, that’s simply not how RDBMS works. The tuples are a B+tree, and in some (MySQL [InnoDB], SQL Server) cases everything is clustered around the PK. If you don’t create a data model that’s easily exploitable for optimizations designed around that data structure, you’re gonna have a bad time. It’s no different than if you decided to use strings to store ints – you _can_, but it’s a bad idea for a variety of reasons.

What you can do is give yourself as much leeway as possible, by following some basic best practices. For example, it’s a hell of a lot easier to update a tiny reference table than to update billions of rows when you decide that column `region` should say `European Union` instead of `EU`.