[dvo]

Toxic seems like a strong word to describe standard relational database functionality. Are you seriously recommending that join functionality always be done in the application layer? If so, are you speaking from specific experience, and can you elaborate on your reasoning?

I've seen too many poor re-implementations of relational database functionality in the application layer to ever recommend it as a standard starting point. Doesn't the concept of not prematurely optimizing apply here? Solve the scalability problem when you need to. That may mean moving some join functionality into the application layer, but the solution to any given scalability problem depends on the specifics of the problem. Just throwing out database joins as a rule seems drastic.