but would not do it publicly -- they were afraid to be received negatively, or in other words, "negative karma".

Karma scores mean that the community doesn't welcome a certain post. If you want lesswrong to be enjoyable for all participants it's reasonable to focus on writing posts that are likely to have high karma.

Apart from that you are a person who hides behind an anonymous handle that is expandly to you. Other people on LW don't hide but have their identities attached to what they write and there the possibility for real life effects.