My general sense is that this is a fairly distinctive quality of social justice communities, so your feeling of alienation may have as much to do with the social justice community as it does with the LW memeplex.

I am very curious to what extent this is true, and would appreciate any evidence people have in either direction.

What is the cause of this? Is it just random fluctuation in culture that reinforce themselves? Perhaps I do not notice these problems in non social justice people just because they do not have an issue they care enough about to argue in this way. Perhaps, It is just availability bias as I spend too much time reading things social justice people say. Perhaps it is a function of the fact that the memes they are talking have this idea that they are being oppressed which makes them more fearful of outsiders.