Ian, some people may be willing to organise the time and venue for their matches but there are plenty of people who will not and it's the people who will not that are the issue.
Some people just don't have the initiative to arrange these things for themselves and, even if they do, just imagine the number of arguements there will be over picking a venue. People have tables they like and tables they don't, pubs they like and pubs they don't. Who is going to take responsibility for deciding the venue when the captains/players can't agree?
There is also the issue of making sure the match is played in time for the result to be given to Fred in time to draw the next round. Fred had trouble enough last season with captains/players not telling him the result of matches that had been postponed. For example, in the quater finals of the individuals cup I was listed as playing against one of three people because none of them had bothered to tell Fred the winners of the postponed games from the two previous rounds. If we leave it for captains/players to do themselves it will just get a lot worse.