I agree, committees are good at saying no. They tend to say no to two not perfect ideas and then force a consensus containing most often the worst aspects of both original approaches. The good news is that the result is so bloated that can‘t be changed and so provides a stable foundation for years of misery.
There are counter examples of course but the power dynamic of committees is not conductive to results that have properties desirable in software.
When I think about the two models, I have Linux as the dictator type and XML as committee designed. Both are functional enough, but the while so few data points are hardly conclusive, I think it's generally indicative.
I'm not a particular fan of XML, even if it's functional enough to get the job done.
Of course you have to find a dictator that is ready to invest all the time and energy to care for a project over a prolonged time and is actually capable of doing so while avoiding to alienate the user base. That's a pretty tall order.
There are counter examples of course but the power dynamic of committees is not conductive to results that have properties desirable in software.