The cost of not deleting obvious fakes and shills are threefold:
(1) posts of actual research and then amplifying posts are further spaced or pushed to the next bread.
(2) more bread production necessary (and less value in each bread)
(3) mis-atrubuted fuckery amplified here or worse, carried over to twatter, fagbook, etc.
The perceived benefits of no action outweigh the risks.