A bit harsh that. I've done some quite high level negotiations in my time and some have involved recourse after recourse to a controlling authority.
My point was not about how you felt about the approach, but how the other party feels. I suspect they were frustrated to be speaking to a monkey with whom they could not reach agreement, rather than the organ grinder. My appraoch in such matters when confronted with 'I am sorry but I have to go back and speak to my members' is to adjourn and ask them to send someone with the authority to negotiate after due consideration, and not to send a note taker.
One will always have to refer to subject matter experts in details technical areas but it sounds like they sent you in to agree to very little and to report back. Professional negotiators are given limits and work within them without reference back as long as they stay within those limits. This is why professionals will often refuse to go in on behalf of one party for example, who might say 'no negotiation' as they know its pointless.