Comment by ryandrake

As a user of native apps, I can always tell when the developer (or, often, the UI designer) chooses to "fight the platform" and reinvent things themselves, instead of embrace the platform and use what it provides for free. Developers who insist controls should look like their own vision, instead of what the platform provides (and users of that platform expect). Apps built this way always look/feel a bit weird and off. Keyboard shortcuts don't work like you'd expect. Accessibility functions that you normally get for free are missing. Controls behave just so slightly differently for them to be odd to work with. The app "sticks out" among the rest of your native apps, and usually not in a good way.

So you end up with situations like: My time picker looks exactly like I want it to look, but it doesn't handle leap seconds. And: My login form behaves exactly like the vision our PM dreamed up, but autofill doesn't work anymore.