Well, I did ask a similar question previously regarding why the build number was needed since users were confusing it with new versions.

Reply from Avast team

Version numbers are important for all users, build numbers usually for advanced users, avast developers and our support team. Every big software companies use it (look at Microsoft and their Windows 10 Insider builds). I don’t feel it is quite confusing, it is just 3 numbers. All our internal systems use these build numbers to track micro-updates, release patches, etc. etc.