Widespread adoption doesn't seem to be a goal, but really as long as the POSIX APIs are supported in a reasonable manner (...or you are Windows), it doesn't mat

Widespread adoption doesn't seem to be a goal, but really as long as the POSIX APIs are supported in a reasonable manner (...or you are Windows), it doesn't matter much. It's nice to use, and it gets to take advantage of portable open-source software which gives it a larger community of developers than (say) Plan 9 and Amiga enjoy, so market percentage doesn't matter much. (Edit: changed "it" to "widespread adoption".)