Linux the platform might want to become mainstrean, but do the people that currenly make up its culture (stereotypical Linux user) want it to be mainstream, or (like in most groups) would they rather keep certain walls up so that the good folks come in, and those more alongside the stream's main path would rather keep away from?

Usually speaking, and in most cultures, the answer is "mainstream is good as long as we don't lose the quirks that keep us differentiated." Unfortunately, to become mainstream means to lose the differentiation of your quirks, and usually means a compromise on some quirks for the simpler good of being in common mind/actions with others.

In other words, teach noobs to use the terminal, and risk losing the quirk that keeps your community unique; and at same time, risk never growing the community and falling into irrelevance because of no growth because you weren't able to take a quirk and keep it from being a requirement.

Simple social science equasion to me