What I mean is that the objective definition of Quality is abstract and not very hard to pin down. However the way that people use it is to refer to concrete 'q

What I mean is that the objective definition of Quality is abstract and not very hard to pin down. However the way that people use it is to refer to concrete 'qualities' that groups of people coordinate around measuring and these are subjective, hard to pin down, but often useful. I agree with you that a common property of a 'quality' is that it can be compared (without this property it would not be measurable.) When people say "this is a quality _______", I think it's useful to ask them why that is Good, and what properties it had that helped them realise it was 'quality'. Plain disagreement about the usefulness of the concept of measuring and optimising for certain properties annoys me, because often the people that do this are just trying to replace the original system with one of their own.