Marketing_Guy - 5:23 pm on Mar 15, 2012 (gmt 0)
It is worrying for the industry that this kind of thing is becoming such a problem. Back in the day there might just be some vague concerns about indexing quotas or PR distribution if you have a bunch of non-value pages indexed (forum profiles, blog categories & tags, ecom site product variations and so on).
A shift to the point where these (actually quite legitimate and common CMS setups) can kill off your rankings entirely is actually quite an aggressive move by Google. The question whether or not it's intentional (clean up your low content pages or get out), or not (oops we thought you were a content farm)?
I can see arguements either way (it'd put a stop to forum profile spamming as a link building technique for example).