Sure it can. But when the technology is able to be commercially sustainable, it must be more cost-effective. If you have two ways to do something and the result is exactly the same, only the cheaper one will stay in demand and the more expensive one will disappear. When one of them has a drawback the other does not have, but it is not a problem most of the time, then it will be the general purpose technology while the other one still remains in use for the special applications in which the drawback would be a problem.
Color photography and black and white photography existed side by side for very long time. Black and white was cheaper and good enough for most purposes, while color was more expensive but didn't provide any advantage in most applications like newspaper pictures or IDs. Except for those cases where you wanted the color and were willing to pay extra to get it.
The ability to teleport letters would not make messengers who carry them to their destination obsolete. Since the wizards provide better service, they would charge more than the messengers. But for most people sending the messenger through the city and having to wait half an hour for the letter to arrive is not such a big inconvencience that they would pay extra for a wizard.
But when you have a swarm of dragons flying by an outpost towards the capital, paying 10 times as much for the wizard than for a messenger would be completely worth it, because the messenger would never make it in time.