Great article! Bookmarking it. Thank you for sharing all of this design wisdom.
Just a single nit to pick here. Flexible designs often perform less efficiently than specialized tools ... but they don't have to. Like software itself, this trade-off isn't carved in stone.
Software and those who design and implement it has the profound capability to be and to do almost anything we can imagine. But hurried, impoverished, MVP thinking isn't going to get us there. Instead, it typically gets us to less flexible AND less efficient tools.
We must dream bigger, all of us, and hold the line when it comes to sacrificing our vision.