I have about 100 followers. I know most of those are probably spam bots. For the remaining, many are inactive. Others have thousands of followers (zero chance of reading anything I write). Tweeting feels like writing in a diary. Or shouting in an empty field. I'm not surprised users avoid tweeting.
There's kind of this cool aspect where you can just respond to anyone and feel involved in a highly visible conversation. But you quickly realize you have a good chance of seeming like a creep for butting into a conversation that, though public, is really intended to be among friends.