Two methods of production can be comparable and have zero to do with quality.
Comparable defined. I'm not seeing a thing in there about quality. If we go by your definition of "most often" then quality should be prominent in a dictionary definition.
Edit: Well, it does show quality in the definition of "compare" below. Worth noting that "similar" is also used in the same lines of denoting quality.
"Similar" used within the definition of "compare". The words are synonyms and carry no arbitrary distinction between them that you are trying to manufacture.