The dot in this instance is more like a dash, 1-10, rather than a decimal. It's like Game 1 Version 10, and we are currently finding our way into 1.9.3, or 1-9-3, or Game 1 Version 9 Subversion 3.
It's due to the format of the update names. The numbers are based on size, not on number. 1.9.x is a very minor update, 1.x.0 is a new version, and x.9.0 is a complete revamp to the game.
For the lazy:
Public Service Announcement: Version numbers are not decimal numbers. 1.7.10 is no more impossible than 1.7.9. 1.7.banana is also acceptable
There are always more confusing examples: https://i.imgur.com/kTW6ZQo.png
I know from .NET that the default version format is version-subversion-revision-build, and I think Chrome is using a similar format. Minecraft, on the other hand, has a much simpler format, similar to JRE (Java Runtime Environment) version numbering.
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