[citation][nom]Cache[/nom]This wasn't about having a version number, but they did not want to be releasing Firefox 6 when you can see Chrome 13. It's a human instinct to assume that the appended numbers mean something, and so marketing kicks in to keep people from making assumptions that Chrome must be twice as good as Firefox because it's got twice the numbers after the name. Same reason Microsoft called it the XBox 360, because they didn't want XBox 2 against PS3.[/citation]
Seems like you're one of the few people that get it. Blaming Mozilla for doing away with version numbers is a little silly, considering that the competition has simply flown with version numbers. Chrome is not necessarily offering 7 versions worth of stuff extra that FireFox 6 currently offers. But psychology will kick in and say "gee, 13 is bigger than 6, so Chrome 13 must be better than FireFox 6." That logic of course falls apart as Chrome 7 was not necessarily better than FireFox 6.
Mozilla's other option would be to inflate their version numbers as well. (as they are currently doing) Kind of like how Slackware Linux suddenly jumped from version 4.0 to 7.0. (http://en.wikipedia.org/wiki/Slackware#History)
In either case, the version number itself loses it's original meaning.