I use the terms when I’m describing poly options in the abstract, but when I’m talking about my actual relationships, I use “husband” and “boyfriend” which I consider more descriptive anyway.
I have absolutely no problem with the terms if they are used descriptively–that is, if they describe a relationship that has grown up organically. My husband is my primary because we’ve been together a long time, we share finances, we pay a mortgage together, we live together, the government recognizes us a a unit…all that stuff.
My boyfriend is not less dear to me, or less part of my emotional landscape, but he is less part of my day to day life. We don’t live together and we don’t share any finances or legal stuff.
Now if primary/secondary are proscriptive I have a problem. If someone announces “I have a primary and you will never ever be anything other than a secondary and you have to accept that” I accept it by walking away. I don’t care if I’m secondary, but I care a lot if I’m boxed in from the beginning, with no chance for organic growth.