Browser on Safari on Mobile(i.e. iOS) could have a different version and not support all the features of Safari on Desktop(i.e. MacOS), the way these browsers

Browser on Safari on Mobile(i.e. iOS) could have a different version and not support all the features of Safari on Desktop(i.e. MacOS), the way these browsers are developed and distributed prevents the cookies from sync in theory, for each request sent via cookie is an opportunity to identify the browser and provide better webpage based on the default api of browser, practically though this would not be required on 99% websites, and would work perfectly fine with sync in place, but that 1% could break, and since there are standard in place, it makes no sense to sync them.