Not sure of what basic ATCO duties you refer to, but maybe PCS' standpoint is based in part on Prospect's point-blank refusal a couple of years ago to even consider the possibility of giving a basic ATCO duty at LL to the ATSA4 grade. This was backed up by a GATCO member stating in the LL VCR that "ATSAs will never do ATCO jobs here - the pilots expect a professional service"
Plenty of witnesses to this one!