I travel often on my own too or join people that I don’t know that well for a travel and people find it weird. Really weird. Most of my friends think I am strange for doing that. I’ve always had issue summing up the reasons why I feel it is important or why I like it but you do it well so thank you for that.
I would add that I deeply believe that being able to be alone today is one of the most important thing. We are so surrounded by social media thus even when we are alone we are not really alone, so we never face pure loneliness, because the moment we start feeling it we turn a phone or computer on. But we have to know to be alone and be okay with it. Traveling alone helps do that.