Let's not forget there are two hazards here. Loneliness is one; the other is the suffocating tyranny of constantly attending to others' ideas and feelings, because attending to your own would be unacceptably disruptive of precious social connectedness. In "A Room of One's Own" Virginia Woolf diagnosed the injustice of a society that reserves the privilege of aloneness to men, and particularly upper class men, while denying it to women (who are supposed to be "selfless") and to a lesser extent the lower classes (who are supposed to be too mindless and animalistic to make anything of solitude.)

Being reluctant to intrude on another's social space is a good thing. It should be joined with skill at inviting others in, and a readiness to respond to that invitation. Let's not shit on people who have solved one half of the problem as if they were inferior to people who have only solved the other half.