It could be coming from competitive sports, where position 1 is the top, and the higher number means a lower ranking. Most DSLR manufacturers use a similar approach (including Sony, with some exceptions). And the 2nd number is actually a revision/version, so that goes up with generations, hence higher is better. Like "Xperia 1 iv (reads Xperia One mark Four)" would mean the top of the line product at 4th generation.

These companies' naming conventions are so confusing. 1 is the top-end model and 10 is the mid-tier. Seems backwards to me. I wonder if there's some logic behind it, maybe based on Japanese culture, like how OnePlus skipped 4 due to tetraphobia. Probably just somebody in marketing not thinking it through.