Stay away from local email accounts with Carriers

Why should users stay away from emails that are hosted from their local internet carriers?
       (ex. YourName@att.com or YourName@comcast.net, etc.)
This question has been asked by many of my customer and friends and I keep on telling them over and over the same information.
An email address is like a home address. Once you give your home address to someone. You'll hope they'll always have it on hand and call or contact you at home when ever they need you.
Your email address works the same way but here where it gets a little funny. Let's say now, you have currently DSL at your home address and move next month. Now your current email at YourName@att.com will probably have to change depending on where you decide to live. So if you move to an area where DSL is not available or DSL is not suitable to use, your 2nd choice is to get your internet access from Cable. Now you loose your email address at YourName@att.com because your no longer with At&t and you now have to create a new name at YourName@comcast.net.
The same goes vise versa for cable. In every way possible you can easily loose your email address and have to create a new one from scratch. Now all of your friends, family and followers will have a difficult time keeping up with you because you keep on changing your email address more than once. And most of them will not probably update your email address because they already aware that you will change it again.
This is where Yahoo, Gmail and Outlook come in.
Now by opening an account with these web based email hosting sites you risk user's from loosing contact with you and they will always remember your email address.
This might not work with almost everyone, but if you do it correctly you will be a step ahead on having a permanent address on the world wide web.