Oliver, thanks!
In other words, the litmus test for me is: what happens when the socially
and politically weakest person in the organisation has an idea?
If we speak of a "product" idea, we have two groups of people - those who can implement the idea, and those who would need to convince others to do it. They use fundamentally different, scarcely overlapping skill-sets. An engineer might go via the "hackathon + demo" route, implementing something simple and showing it to gain traction. A non-engineer would start with the social aspect first - talking to others if the idea is worth pursuing, how hard is it to do, and eventually - convincing others to allocate their time/resources to do it. Sometimes an engineer may go the social route instead, but it would be very hard for a non-engineer to engage in development. Lastly, the "designer" group has an amazing skill-set to visually present their full vision rather than the demo, thus often having easier time of conveying their thoughts.
In a sense, the barrier of entry for the person in the "weakest position" would not be as high for the "doer" as for the "inspirer". So I think the real challenge is how do we capture and evaluate those ideas from the second group? Also, no matter how hard we try, it would be either very hard, or very expensive (and not just financially) to force the implementers to do an idea they do not believe in. So in a sense, doers need to be persuaded first and foremost.
As with any explanation, a picture == 1000 words, so we could promote "idea visualizers" - designers who are easily approachable and could help to draw up a few sketches of the idea.