No one's asking for bulletproof validation. What I want out of input[type="fancy"] elements is: 1. Better detection of the platform than I can do myself. That

No one's asking for bulletproof validation. What I want out of input[type="fancy"] elements is: 1. Better detection of the platform than I can do myself. That leads to a UI targeted at the platform (different default phone keyboards, etc). 2. Uniform UIs across websites. I hate having to learn a new calendar widget on every website, it's worse for regular users, not to mention any users that need accessibility features that are prooobably not included in most home-rolled (or even popular) widgets. 3. Basic validation. Just to help the user a bit. I'll validate it again on the back-end, and I might even be validating it myself on the front-end. But basic validation helps and, once again, that uniformity thing shows up again here since the user could be aware of how that widget reports errors on their platform already and could be looking for them.