What if I copy something but accidentally get another couple words one of which is a number. For example copying from a chat app and get the date with the message. Then my "Sep 24th 416-555-1234" input which, would have been very easy to fix, becomes 244-165-5512 34. It will take me a few seconds to realize what has happened, identify where the intended phone number starts and remove the accidentally pasted digits.
The nice thing about the native input is that it is very simple, predictable and flexible. It may be easier to make a better UX on the happy cases but it is very difficult to not add some suboptimal and confusing UX on the less happy cases. Often times it is best just to keep it simple so that the user can easily complete their task rather than adding some "magic" which may backfire and confuse users.
It is surprisingly often that I need to open a text-editor or clipboard-editor to format values before pasting them into apps or websites because they have broken an input field by trying to be magic and failing to consider anything but the happy cases and maybe one or two bad paths.
