That's non-optimal UX imho.

I can't understand why it's so hard to get a decent datepicker in general.

You should only:

* Tap on years and months to select one

* Tap on your preferred day

* Being able (programming side) to select a range

* Being able to input your date inside a preformatted text field that can validate it

Windows from 7 to 10 nailed it, period. So bad that's for desktop-only users.