The idea is based on a few aspects that game developers almost universally share: they are trained to think of new, innovative ways to solve problems since each new game has to push the boundaries of what was possible before, they tend to be passionate about development and doing cool things with code, they are hardcore about optimization, and they are used to constantly learning new technologies and algorithms.
That said, not all aspects of game development are ideal for other projects, especially on the web. As others have mentioned, web development requires a very different mindset than game development. One major example is that game developers often build components from scratch, rather than re-using existing ones. One of the hardest skill for me to learn was to avoid "reinventing the wheel" and using pre-made off the shelf and open source components in projects.
I am definitely biased, but my own experiences have caused me to pay more attention to resumes I get that list game development experience, but not to the point of excluding others.