Windows 3.0 to 3.1 to 3.11 to NT (but not really because NT is a different code base) to NT 3.5 (where did 1.1-3.0 go?) to NT 3.51 to NT 4 to 95 (wait, 95 is not from NT but from 3.11, right?) to 98 to ME (except ME is a cross between 2000 and 98. 2000? Opps!) to 2000 (which is really NT 5) to XP (which is really NT 5.5) And, that is ignoring the the MS Server OSes!
My point? Each and every software product or project chooses and changes it's own version numbering scheme at will. Even proprietary ones.
Would it be good for all the project to follow the same numbering convention? You bet! But the confusion caused by the current situation is not limited to the FS/OSS realm. It is confusing or not based on how each software product does it.