I see that, but you don't talk about this - your main point - in the case studies, at all. Of course it's difficult to, since they don't discuss it and so you have to infer it, but if it's your main point, you probably do need to mention it in the case study.

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