If I'm not mistaken, .net was part of the original internet and was the extension for network providers. Com was originally commercially popular because of its specific "commercial" designation and was 1 of 3 that were available for unrestricted registration.
.com - commercial
.net - network
.org - organizations
.edu - education
.gov - governments
.mil - military
.int - international
All subsequent tld's such as biz, info, aero, travel, pro, name, jobs, coop, cat, museum and the country codes continued to define content on the basis of the content provider. What kind of entity you are, what type of business you are in or where you are located, etc.
Then came .mobi as the 1st tld that only cared about the user. For us registrants, mTLD doesn't care about where you are or what type of business you are in. Their only concern is that we provide our content in a way that is usable to mobile users. It is a completely different way of looking at the purpose of a tld.
From what I can tell, .tel is a completely different beast with a completely different mission from .mobi.