This is really solid advice, I think. Either you are building something for learning, or you are building something to ship it, and it's better not to mix the

This is really solid advice, I think. Either you are building something for learning, or you are building something to ship it, and it's better not to mix the two. If you are building something to learn new technology, then use whatever that excites you to make something that you won't feel guilty throwing away. If you are building something to ship, then you should preferably use nothing that you haven't already used before. You'll still improve as a developer, because you will get better at technology that you have already invested in.