I'm 100% with you except that modern native datepickers are awful. On iOS, selecting a date that is some years in the past or in the future is painful and entering the wrong date by mistake is really.
But I agree that it doesn't mean that it's up to the application developers to fix this.
The worst thing that can happen to a website is to use a custom scrolling logic/scrollbar. It never behaves correctly.
Next step would be discovering that we have been doing this since Windows 3.11, and we lost this ability because of web programmers.