With this in mind, it wouldn't make sense to mark 0.18 stable before most of the above is finished. We made 0.18 a major version because it will break mods with all the changes we are making, and while initially it hasn't broken that much, many things to come will have a bigger impact, such as the Character GUI.
As a software developer and game programmer myself, surely this is the antithesis of the version system
1.2.3
1) most major of content changes, Will quite certainly break derivative works
2) Major content changes, including new content, will quite often require refactoring of derivative works
3) Bug fixes, content balancing, derivative works safe
I suppose I am somewhat prone to forgetting that factorio isn't at "version 18" but actually "0.18", but would still expect mod breaking changes to tend to get restricted to level 2 changes, where not absolutely necessary.
That said Unreal Engines build pipleine complains at me every time I compile that my SDK version is (numbers just for example) 1.2.3.0041 and it wanted 1.2.3.0001