The comments do matter but are minor. Like iceman said it depends how much horsepower is behind it. The NPRM process recognizes that the different lobbying groups get in early and participate in the writing of the NPRM (normally a couple years). The comments are a way to let the general public comment. Do they listen-- yes. If an overwhelming number of comments say no to the 10 hour duty, they will look to see if one of the groups was "suggesting" it to their respective folks. If it appears to reflect general concensus, they'll take it into consideration. The age 65 NPRM showed the politics of the process. Virtually nobody in the US wanted the age 65 but the ICAO had switched and the FAA was in a bind to harmonize the FARs so....it didn't really matter what anybody wanted--it had to happen.