I use web browsers only, but a very, very large group don't, the use their portable device. In fact I doubt most people even know they can text from their desktop, if they even have one. Fact is most everyone has a cell phone and keep it with them24/7, so that is there preferred method of communication, us desktop users are just a tiny fraction of the people who participate in this forums.
Not a bad point.
One other thing that I just now thought of: Think how popular you’d be (+ potentially pulling in some significant extra bucks too), if you provided people with some (unofficial) instruction / tutoring on how to text from the desktop. Could have yourself a nice little cottage industry eventually ... :-)