Bob was trained by the great manager Tim. Tim endorsed Bob from internship to junior engineer to senior architect. Steve and Phil both later recommended Bob for promotion to CTO.

Then Bob screws up big time. The board of directors gets involved. Bob is fired and eventually gets a new job as a middle-manager or lower in some other firm, or if the screwup is large enough, takes early retirement.

The "guild" is doing the same things as a company does. But judging skill, success and failure is quite subjective. That's why we need so many competing firms to get results. A single guild would be like everyone working for a single company. It'd yield very poor results.