Caching is an abstraction, not an optimization

What? No, caching means a specific thing: keeping a copy of data away from the source of truth, closer to where you want to read it. Caching always makes systems more complex, it never makes things simpler, and it damn sure doesn't serve as any kind of abstraction unless you're redefining what words mean to indulge your technical philosophizing.

What if you have to keep some data closer and away from the source of truth though? Given that constraint, TFA argued that other architectures could do the job but that caching functions as an abstraction.