It's an awful thing if you think about it. A person's perception of what other people think will be heavily skewed when ~10%? ~20%? of comments are removed. But it's way worse than that because when things get so heavily moderated, people simply stop voicing their opinions in the first place. So you're not just missing 10-20% of the whole picture, but maybe add another 50% due to people being trained to not voice opinions that will meet some moderator's saintly knowledge of what opinions people are allowed to voice.