I totally agree that the Commitment Curve is great as a theoretical framework, since if basically maps a conversion process. Do I think all of my users nicely fit along that curve and will allow travel in tandem along the same scientific curve? Heck no.
I think its usefulness is in providing a paradigm for conversion and in pushing users to the next stage. Some users will never move past the first stage on the commitment curve (aka Lurkers), and thats okay. Some users will blow through the first three stages in their first week and become your superusers. But I think several of it’s tenets - like prioritizing your asks from small to significant - are important concepts to understand in providing a journey to your users.