I have always thought that the word "concern" was not necessary, I personally use the word "module", and only use "concern" in contexts in which people around expect that word.

We do not fully agree that Ruby mixins are supposed to be "traits".

A Ruby module is something way more generic than that in my view. In particular, splitting a class into chunks of related functionality for pure organizational purposes is for me a valid and idiomatic use case for modules.

Additionally, let me leverage this message to underline that a "concern" is something conceptual and does not need to extend ActiveSupport:Concern. That module is a utility that simplifies certain patterns that you'd implement using included/extended in a simpler way. But if you don't need them, you don't need to use the utility.