it's psychological. when chrome, safari, and internet explorer (and i guess opera too) all have higher numbers of version numbers, naturally people associate 'modernity' and therefore functionality with higher version numbers. so it IE is at ver.10, safari at ver.6, opera at ver.12, chrome at ver.7, and then firefox is still on 4.7.16.74......you're not going to think of using firefox or trusting that it's keeping up with the modern browser market.