Actually, they understand it quite well; fixes to released versions of Firefox use dotted version numbers like that. Mozilla just switched from doing major releases on a timescale of 1-2 years to doing major releases many times per year.
Among other things, that has improved the quality of the browser, since features don't have to rush to meet the release deadline when they can just wait for the next one right around the corner.
But nothing has really changed, except what they refer to each release as.
I've always been a fan of this definition:
A minor release contains bugs fixes and minor feature changes (For example, 1.0 to 1.1). Major releases include major functionality and feature enhancements (e.g. 1.x to 2.0).
The problem comes in that they're releasing minor bugfixes and patches as major releases, for no other reason than to compete on the numbers system.
I don't think the answer is "abolish the numbers", I think the answer is "be honest".
Among other things, that has improved the quality of the browser, since features don't have to rush to meet the release deadline when they can just wait for the next one right around the corner.