If an article looks interesting, I usually comment saying, "Sounds interesting; I'm not going to use that social reader app, but I will look up the article later." That lets people know that if they really want their friends to read an article they'll get more bites if they post it as a link. Fewer people using the app does affect the market, and the plugin removes the main disincentive to using it, which is that your friends will ignore the links you post. It's better to raise awareness of that disincentive than to bypass it.
