Everybody has unlimited texting on their phones now so there's no need. There was a time when unlimited texting was rare and not all phones even had SMS, so it

Everybody has unlimited texting on their phones now so there's no need. There was a time when unlimited texting was rare and not all phones even had SMS, so it was popular to use various free web-to-SMS gateways if you were at a computer and your recipient may not be. I used AT&T's gateway in particular to message friends for a few years before I got an SMS phone. There were also shady ad-strewn "free texting" gateways, some acting as frontends to the official ones, some with a Turk behind the scenes, and even some that didn't work at all but just faked a texting interface to serve up ads.