This is a good idea, in theory. However, as any system scales up, various key roles become more professionalized (and expensive) and the economics have to make good sense as a business. You can't rely on altruism and hobbyists at a large scale, especially for something meant to be sustainable over time.

I don't think we should rule out witnesses serving because they are interested in the project, nor is there any real danger of that happening any time soon, but ultimately resources aren't free. The best case are witnesses who are personally committed, but not required to make unrealistic personal sacrifices to keep the system running.