In general, framework owners _want_ you to become tightly coupled to the framework, whereas as a user you want to be able to move away from it more easily. I think this conflict of interests is behind recommendations like this, rather than sound technical reasons.
Why would framework owners want you to become tightly coupled to the framework? They're basically just offering a set of solutions that come with some tradeoffs, but they don't intentionally create problems for their users.
For framework owners that have a business built on top of their framework, that tight coupling is their "moat" that helps keep you locked in as a paying customer for longer.
