Someone with particular accessibility needs might not be using a popular desktop browser - they'll already be using a user-agent which is adapted to their own needs.
If you use native input elements, then whatever accessibility needs a user might have can be accommodated by a user-agent which caters to those needs. And you get that to take advantage of that for free.
If you roll your own, you can't cater to people with disabilities that you haven't considered.
Accessibility is not black and white. I have good vision, and native date pickers as implemented in all desktop browsers, are so tiny, I have to zoom the page every time I encounetr them.
> If you roll your own, you can't cater to people with disabilities that you haven't considered.
True, but you out of hand dismissed huge swaths of people who are not using "adapted user-aganets" but still suffer because browsers have a shitty native implementation.
If you use native input elements, then whatever accessibility needs a user might have can be accommodated by a user-agent which caters to those needs. And you get that to take advantage of that for free.
If you roll your own, you can't cater to people with disabilities that you haven't considered.