This is definitely part of it, but it doesn't quite explain the level of hostility of some people to me. I think there's a sense of "cheating" coming into play. Self-publishing, to these people, seems like taking a short cut around a lot of difficulties people assume they HAVE to go through, not least because they were TOLD that at some point.
It's the same sort of hostility reserved for those born to money, for example.
I was just talking with my spouse about how the technological revolution is changing things, including the rise of crowdfunding as a truly viable income option. As always, people are going to resist these changes, and I think one group will be this group, that feels like bypassing "traditional" publishing is "cheating".