This site focuses on 2 forms of communication. The first is email, and the second is postal mail. I am sure it is apparent to many, but I will go into the main differences I can see.
Email is quick, cheap, and less likely to make mistakes in writing the address. Someone on the other side of the world can send an email, and it will get to me almost instantly. It’s not guaranteed that I will reply immediately, but it will be in my email provider’s server immediately. This is a benefit for most people that would want to relay some information quickly. It is also cheap. Paying for a postage stamp can add up, and international stamps even more so. I knew a couple of people that would not write to someone out of the country due to cost of postage. With email, you just need an internet connection, and you can send email. Even getting an email address can be free. Also, email is easier to address. You just have to write in the form of uid@provider.tld. In my case, my address is frank@fsp.ws. This is much simpler than my postal address.
Postal Mail
With that being said about email, one might wonder the benefits of postal mail. For some, there is the nostalgia of actually writing a letter. Such people will prefer written letters in return. Because of my handwriting, I type all of my postal mail. Also, one could send gifts. You can’t send tangible items over the Internet. It’s just not possible. With that in mind, a postal address is needed. Even if you acquired the postal address via email, you still need to send a package to a physical location for it to be received.