reddit.com: Pycon 2008 disappointment
All of this is to say that it is possible to get sponsorship without selling the conference. Not only that, but our experience with PPW suggests that all parties - including sponsors - benefit when the conference remains focused on the attendees' interests.
I think this is important:
Surprisingly, we got lots of sponsorship. Moreover, our sponsors tended to be companies that "got" the programming community and that our attendees were more likely to be interested in. In the end, our sponsors were happy and our attendees were happy.(My emphasis)
The wisdom on conferences is obviously based on the more general case where the audiences can be very varied in interests and in experience - when manning a booth I have been quite shocked by the lack of research by some attendees, but more imprtantly their lack of focus on what they wanted from their visit.