I've seen salesmen assure the customer that the product will, in effect, can safely ignore one or more of the fallacies of distributed computing, or that it has solved the Byzantine general's problem.
It becomes a colossal waste of time for engineers to have to unwind/correct such idiocies.
Engineers being in the loop at each end helps avoid that. When that happens it is merely a matter of taste as to whether all the engineers and salesmen can sit around a table together.
Not all businesses are like that.