Nico is right in saying we don't choose who decides to participate. But we do influence that choice.
In particular, we can decide which communities to approach to invite participation from and we can encourage or discourage people who come to participate. We are not the passive captives of fate that some folk seem to suggest.
I first started participating in IETF 25 years ago but I have not participated here continuously.. One of the reasons for that was that I did not find IETF an inviting place to work. Folk would proclaim with great certitude 'facts' about the nature of URLs and explain how it was necessary to 'fix' the 'broken' architecture of the Web.
It is really easy to drive people away, all you have to do is to make it clear that you are not listening to them or interested in their input. Rather too often, I see people put in the position that they can only get their point across in ways that are interpreted as 'shrill' and 'emotional'. [Though it should be noted that we recently witnessed in another venue the very people who denounce such behavior from those punching up immediately endorsing and supporting such behavior in an individual punching down.]
Listening is really difficult and the IETF organization is not particularly well suited to listening. While we do make some use of use cases and requirements analysis these days, I don't think we do it honestly. WGs select the use cases that support the implementation they have already decided on rather than allow the use cases to inform design. The tell is that the criteria for accepting the use cases is whether the implementation supports them.
Finally, unless you happen to be Dave Clark or Vint Cerf and you happen to be designing a packet switching protocol to support a WAN of 10-1000 nodes using 1970s technology, attempting to emulate their mode of work is irrelevant. We are not re-designing IP. We are trying to manage the social and technical consequences of the network scaling to ~10 billion users and ~1 trillion nodes in the coming decade.
We are attempting to solve different problems and we need to consider different approaches.
