I agree with the premise of validation, then building. While this is a good rule of thumb, it's not always possible. I like the focus and thinking behind getting users. It can't be "built it and they will come". Having a good, sound plan and sticking with it is the key.
You don't always need to prove out all your growth channels. But it's important to have strong hypotheses and remove at least a little bit of uncertainty around those hypotheses before building.
It is a situation where both are required (`&`).
Good luck with the projects!
Your heading "My side projects always fail" makes me think the problem is getting initial adoption (not going from small adoption to huge adoption). The network effects of those three examples don't kick in until after some adoption.
I like the idea of considering not just the product or the market, but also how you to reach that market. It can change your choice of which idea to pursue in the first place. Really, to evaluate as a business idea, not just as a product idea
I suppose at this point in the article, if you're not yet convinced that distribution is half the battle, you won't care about the rest of the article.
Now I know what you meant, this really is just nitpicking.