The most common complaint I've heard was rather different: nobody questioned that some pruning is necessary but complained that the standards were incredibly arbitrary and niche interests like anime characters or minor porn stars frequently made the cut while e.g. academics were deleted because they didn't have a mainstream book, New Yorker article, etc. and the deletionist cadre wasn't interested in widely-cited papers, broad recognition within a particular field, etc.
Jason Scott also highlighted a similar problem in http://ascii.textfiles.com/archives/3826 noting that the question again has never been quality but a very small number of people deciding a topic wasn't of interest to anyone else despite demonstrated activity.
Attempting to portray this as a question of spam control or lack of external sources is either uninformed or whitewashing.