This is a good point. But it only goes so far. Ultimately, even code and toolchain flexibility comes at a cost - for example, should you go for a non-relationa

This is a good point. But it only goes so far. Ultimately, even code and toolchain flexibility comes at a cost - for example, should you go for a non-relational database because of potential future scalability needs, or cross that bridge when you come to it? Or should you make your code internationalizable, even though the first release is in English only? The right answer may depend on the probability of the business need occuring in some foreseeable time frame. Unfortunately, the OPs point is too black and white, where the reality is much more grey. In my view decisions in a project need to be subject to a cost-benefit trade-off, and future-proofing is no exception.