> Unfortunately some browser vendors were reluctant to add new content negotiation-based solutions, because of past bad experience with this kind of solutions.

Can anyone provide more details of what they're talking about? I'm actually not too interested in naming names of browser vendors (which they were trying to avoid clearly) -- I'm more interested in details of the 'bad experiences', what was it (some people) thought went wrong with what particular aspects or areas of con-neg-based solutions in the past?