Yeah, irreplaceable is probably the wrong word. But in an industry where personal relationships are a huge part of the business and a single person can really

Yeah, irreplaceable is probably the wrong word. But in an industry where personal relationships are a huge part of the business and a single person can really have a large effect on the bottom line it makes sense to do something like a partnership. If I am personally bringing $5 million in bookings each year why would I stay at a firm that just pays me a salary when I could just go out on my own. Whereas as a programmer it's not quite as cut and dry. So the partners aren't irreplaceable I guess but their bookings have such a direct impact to the bottom line that the marginal value of them as a person is almost 100%.