I pointed a domain https://www.example.com to https://www.example-2.com by updating the @ and www A Records in the DNS settings of https://www.example.com, to use the IP address of https://www.example-2.com. This seems to work.
Why do hosting providers like SquareSpace then ask to update CNAME records as well, if pointing can be done by just changing the @ and www records?
Any clarity on this would be very appreciated. Many thanks!
They need to be certain that the owner of the domain really wishes to delegate control over what content will be hosted on his domain to that specific SquareSpace Account. If the Domain was hosted with them, they would know this already.
But since you are linking an external domain, they need to ensure they are not helping facilitate abuse. If they did not require you to place a unique code in your zone, someone else would be able to add your domain in his account, unable to tell apart legitimate owner and impostor.
The code is identifying your account (to them, not necessarily to the rest of the world), so seeing it in your domain tells them you are the owner.
BTW, they do not require you to use a CNAME record. Its just one method of unambiguously linking the domain to your account. Documentation mentions adding a TXT record with that code in the zone root is equally valid.
