Hmm, I am thinking (since I have had issues along these lines myself) that the OP is probably referring to one of two things, or perhaps both of them. One is that many people on CAF seem to have a “take or leave it” approach to “admonishing the sinner”. Instead of really getting down to reach people at their level, they say “this is the TRUTH and if you can’t take it, too bad”. I suppose that may be par for the course in the “Moral Theology” forum, but I’ve seen it take place in the Family Life and other forums as well.
I also agree that many people (and this is not just CAF posters) feel more comfortable judging people for sins that they themselves are not tempted to commit. For example, the harsh judgment levied not just against sexually active homosexuals, but anyone who identifies himself as “gay”, repeated statements that the state of being “homosexual” is in itself sinful, and the approach some people take of homosexuals as a group being the “enemy” not deserving of any charity or compassion (for example, the recent suicide of a teen who identified as homosexual was taken as an opportunity to just rail against how “the homosexual lobby” was going to use this case to further their cause…not that this was completely inaccurate, but the way it was expressed seemed quite insensitive). There often seems to be an “us against them” mentality where the priority is not evangelizing or converting people, but simply defeating them; a mentality that seems to be far more political or military in nature than fit for a religious forum.
Or, the OP may be referring to people who make statements that they imply are “true” Church teaching when they’re not; for example, a mother can only work for pay if the alternative is starvation; a couple can only practice NFP if another pregnancy might cause death, disability or destitution; all parents MUST either send their children to Catholic school or homeschool them; dating is inherently sinful, while courting isn’t; a female must be under the authority of some man (either father, husband or other male relative) from birth to death; marrying a non-Catholic is sinful (as opposed to just a bad idea), etc, etc, etc. Or, people who state things like, “I’m living in a shack without running water with five kids, homeschooling them all, and I’m not even tempted to use NFP; if I can do it, you can do it.” I tend to call that a holier-than-thou attitude, but I guess some might call that a fundamentalist one
Another example I just thought of is, the recent news about how a pregnant woman decided to forego chemotherapy for cancer and died shortly after the birth of her child. While most posters expressed admiration for the woman’s sacrifice, there were some who felt compelled to point out that the woman was not married, and seemed to think her committing the sin of premarital sex totally cancelled out her later heroic actions (which aren’t even required by Church teaching…yes, St. Gianna Molla was canonized, but from what I understand, if she had chose to undergo treatment for her illness, she would not have been sinning). That’s the kind of attitude that seems more in tune with Westboro Baptist Church types than Catholics with compassion.