I don't feel this situation is the same.
Microsoft didn't win for two decades by nibbling small potatoes off of everyone else's plate, they won by persecuting swallowing entire industries that were evolving rapidly. Word processing, fileserving, WWW access, telephony, video gaming, SQL, e-mail, ad infinitum...
Instapaper is not an industry of this scope - it's a single webbrowsing feature.