Precisely, it's not unreasonable for two business owners preparing to engage in a long term relationship sit down with each other to discuss the terms.
Once the work is underway it's perfectly fine to delegate responsibilities to subordinates. After all, that is much of the point of the service. To get IT issues out of your hair so that you can work.
And, lets face it, if you were actually delegating responsibilities to others, then it's those others who should be involved at the outset.
I fully believe, in many instances, when someone several to very many levels removed in the management hierarchy says, "I had no idea that was going on," when confronted about something. And for all the, "The buck stops here," claims the fact is they shouldn't know, or have needed to know, because the direct managers of those misbehaving, not following company policy, etc., are in the position, morally and practically, of having prevented or stopping whatever the issue/behavior was. But we also know that frank and honest communication "up the chain" is never encouraged, no matter how many claims are made that it is.
I have no need to be dealing with the CEO (or equivalent) when it's the accounting department that needs the service. In fact, were I to be asked to go through the CEO (or equivalent) on a routine basis I'd fire the client. That's just plain stupid, and I have the choice to indulge in stupidity or not.