On the other hand this is the other side of the equation: 1. As platform evolves, a system built on a dead product is itself a dead end. 2. Developers skills

On the other hand this is the other side of the equation: 1. As platform evolves, a system built on a dead product is itself a dead end. 2. Developers skills are also dead ended. 3. All the supporting products (build systems, test systems) are also dead ended. We seem to reinvent new ways to do old things (forms, validation, saving to database), and this is very wasteful. Part of the reason why the web has grown up so much is that it has enough time to evolve. I just saw WebStorm and it was amazing. You know what? This is possible because the browser as a platform has enormous incentive to maintain backward compatibility.