But you're entirely right in that Accenture isn't considered a part of the Big Four accounting firms precisely because its skillset is advisory rather than accounting.
But this is a meaningless exchange at this point. haha
But now all these companies are bleeding over into each others business areas - many do strategy, operations, implementation, accounting.
All Big4 firms had to shelve their IT consulting to separate divisions or into new companies which most later sold:
Arthur Anderson formed Anderson Consulting which later became Accenture.
Ernst Young - Ernst & Young Consulting which was acquired by Capgemini
PriceWaterhouceCoopers sold to IBM Global Services
Deloitte retained its consulting division I think
KPMG - KPMG Consulting - Bearingpoint?