Humans. We are an erratic lot.
Somebody posted a link to a similar thread on DPRforum and, surprise, they were complaining about exactly the same sort of bias as people are talking about here. I suspect that, regardless of how moderation was handled in the dying days, people would not be happy. Their forum has been unceremoniously and abruptly killed.
My impression from my time on dpreview is that some people have very strongly held views about some things relating to photography and could be rather aggressive about those views. On an online forum where you do not get real time, non-verbal, feedback those strongly held opinions can lead to less than optimal outcomes and perhaps hard feelings towards moderators.
FWIW, I've not had any issues with moderation at dpreview.
Also FWIW, I participate on a forum where political discussion is allowed. It can get fractous and there have been a few bans for people who let things get personal. The site owner has most likely made a decision to moderate with a very light touch and made it work on the most contentious possible subject, so even handed moderation is possible. I suspect it takes a lot of effort on the part of site management to get to some level of consistency.