I've never understood this "every program on my device should look like the same company designed it" mentality.
Nothing against using the pre-built ui components provided by the OS, but looking down on a developer that decides to use something else? Just weird to me. A checkbox is a checkbox, it really doesn't matter whether App A's checkboxes look identical to App B.
Now, if App A's checkboxes look different than App A's other checkboxes, then I'll complain.
Having things look the same makes everything easier to use. I know exactly what's clickable and what happens when I click them, instead of having to figure it out each time.
I don't understand why you'd be annoyed at different checkboxes within an app but not at different checkboxes between apps. Do you only ever use a single app? I constantly switch between many apps.
More importantly, having things behave the same makes everything much easier to use. If your checkboxes don't work the same way as the standard ones (and yes, this is a thing that happens) then that's a problem.
In addition to intentional behavior differences, you also have bugs. For an example close to my heart, Slack often loses its mind and destroys my input when I try to use the Undo functionality. This sort of bug would be impossible if they just used the standard UI widgets built into the OS, because the OS's widgets have competently implemented undo.
I love it when someone's example makes it clear that they have no idea what they're talking about.
OS Widgets don't implement undo. Undo is inherently tied to app state and the developer is responsible for managing it. At most, the OS will give you an undo button/icon and you can use it to fit in visually.
Frankly, building a separate version of my app per platform to conform to your nativist standards is a huge waste of time. My UI will work across all target platforms. If you can't figure out interfaces that aren't straight out of an Apple/Microsoft design document, that's on you.
It's mental overhead; if App A's checkboxs look different than the ones in App B, then I have to switch that mental context every time I switch windows. If everything uses the same controls, then that consistency means users don't have to think about the controls.
Nothing against using the pre-built ui components provided by the OS, but looking down on a developer that decides to use something else? Just weird to me. A checkbox is a checkbox, it really doesn't matter whether App A's checkboxes look identical to App B.
Now, if App A's checkboxes look different than App A's other checkboxes, then I'll complain.