There are birds where the physical appearance is probably pretty useless compared to call. All of my Empidonax flycatchers were seen AND heard, because ID by sight alone for that group is a nightmare.
As for the ABA...no one from the organization is going to bust down your door and make you count heard only birds, or otherwise police your lists. They are not so much telling you what and how to list, but offering some general guidelines, which you should probably follow if you decide to volunteer your list totals for publication. The only really solid concrete thing they do to regulate lists is to define the ABA area and to accept or reject new records.
Personally, for life birds I have to physically see a bird, but if I later need it for a state or county list, heard only is fine. But I don't really care what other folks do. For me personally, I am a visual person and have poor hearing, so I just feel a lot better about counting things I see.
Exactly so and rather than 'publication', the more important word is 'comparison' because you need a standard reference point.
It would be like going to buy a piece of wood and having asked for a piece 3m long, you call the woodyard when you find it's only 2.9m, to be told, 'ah but we don't measure from there, we measure from here'. :t: