I think the "fundamental social contract" is about communication, not numbering systems, which, despite your assertion, are obviously still a point of significant disagreement and divergence. I thought the KDE team communicated the meaning and intent of the 4.0 release quite clearly. I might cut some slack to a novice user who was surprised when 4.0 was dumped on him/her, but it's just plain weird to hear those kind of comments from LWN readers, whom I expect to be better informed.
It's impossible to escape the conclusion that there was a cadre of people out there -- not novice users at all, but really, power/expert users -- who, despite knowing full well how the KDE team had characterized the 4.0 release, insisted as a matter of highlighting a "higher" principle (the ".0" principle) on installing it and treating it as what they insist a .0 release should be, and then using any negatives from that experience as ammunition and fodder to attack the KDE team -- all to grind into the face of the KDE team (and the rest of us) -- the consequences of messing with their beloved ".0" definition.