IE11 is supported on Windows 7 and 8.1, but not Windows 8.0. So on 8.0 the auto-update feature is ineffective. According to StatCounter only 5% of 8.0 users have updated to 8.1. There must be something blocking people there, not sure what it is, but end result is the auto-updater doesn't actually auto-update everyone and fragmentation gets worse.