Is Unreal Engine for game developers or for engine troubleshoothers?

I’m using master branch of engine on my project (switched from promoted recently).
If you are not not modifying engine code directly, it makes sense (at least for me). Yes I have issues as master branch have latest and untested code, but on the other hand, maintaining my own code is easier. Since I don’t have to make big changes every release (when there is a lot of changes at one time).