Because the naming convention was used for chips based on Skylake microarchitecture (but with other differences such as process node). Not changing the name implies they've either changed the naming convention (why?) or they haven't improved the microarchitecture since 2012.

>they haven't improved the microarchitecture since 2012.

No, but they did beat 14nm like a dead horse for almost a decade. So you're not that far off.