The "all things are nails, always use hammers" mentality is almost explicitly what I am arguing against.

My mention of SQL was particularly deliberate. It's an especially successful high level declarative language with clear semantics. Implementations provide sophisticated execution engines for optimizing and efficiently running queries. It is quite a lovely separation of concerns that gives you great flexibility and good performance.

Obviously SQL would be a disastrous choice for, say, storing the pixel data in your video codec. Meanwhile, hand-coded C data structures and algorithms would be a disastrous choice for an inventory management system. Tradeoffs everywhere.