Same thing for people claiming they don't need any frameworks.
But this is not what people usually call as ORMs. All the "bad kind of ORM" (JPA impls, Entity Framework, SQLAlchemy, Doctrine, Active Record...) have some concept of an entity session which is tracking the entities being processed. To me, this is a central feature of an ORM, one of its major benefits. It is, incidentally, also serving as a transaction-scoped cache.
I won't of course dispute that you can have caching on other levels as well (which may perform differently, for different use cases).
To his point: It's very hard to beat decades of RDBMS research and improvements
Your RDBMS internal caching will likely get you extremely far and speed difference of Redis vs RDBMS call is very unlikely to matter in your standard CRUD App.
To any juniors reading: cache the response payload (or parts of it), not the results of database queries.
Forgive my ignorance, but how do ORMs help with adding caching? Or are you implying they obviate or reduce the need for caching?
Why is caching not a feature in DB connection pools? I mean, most databases have it on their side, why not have it as an option for the same query sets prior to hitting the db, with configurable invalidations? Or is it, and I've just never thought to look for it.
Example: if you execute "UPDATE orders SET x = 5 WHERE id = 10", the connection pool has no idea what entries to invalidate. ORM knows that since it tracks all managed entities, understands their structure, identity.