I think it's more that most people are too afraid for their jobs so most posts are made with the assumption that the boss is watching (big brother) and that they better either brown-nose if it's an opinion or stick to neutral tech topics. I've noticed a lot of pro-management posts lately which means an influx of managers and brown nosers and seems to substantiate that portion of my theory.
Also, increased workloads for those left standing after layoff rounds to contend with doing the jobs ofmany people by themselves also seems to contribute to the decline of any good discussions since the old management maxim applies here, "If your people have time to complain you are not keeping them too busy to think, and we don't want employees thatthink without management telling them what to think and when."
It all combines to make Jack and Jill Techie very dull people who have very boring discussions and no real substantive opinions.