I think that's a fairly myopic, though unsurprising, point of view from the sales perspective. There's tons of work that goes into making a viable product that gets the paperwork to be signed. Programmers, teams, etc. are just as (ir)replaceable as sales staff; when you have the right combination, everything works well. Handshakes and signatures are the final step of making a deal, not the defining ones. From a bare financial point of view, once the paper's signed, you can change your company all you want, but unless the product/service continues to be well-made and add value to the customer, the money's not going to keep flowing. Engineering talent is not exactly fungible.