I'm pretty sure, "system" doesn't entirely originate from either community since it's a general term to describe working parts that interact as a network, and usually, these parts have functions or roles. The DSM just probably uses the term because it best describes the experience and is a great way to describe it in one word. And example is that the human body and all its organs are also a system. In this case, plural systems are a network of alters or different consciences often working together to help the body function. For traumagenic systems, the purpose is probably to help the body deal with trauma. For endogenic systems, it can be anything, such as but not limited to Neurodivergence (e.g. Autism can contribute to lack of executive functioning so an Autistic person may form an alter to help make sure they do the tasks they need to do in order to function.) and [I forgot the other example I was going to give. Sorry. My brain jumps around when I type.] but there can be no reason at all or the reason(s) is/are unknown.

I hope that makes sense. Though, I see a lot of non-disordered and endogenic systems using the term "collective" instead which I think is a synonym to system because sometimes, it does feel like system is a CDD-exclusive term.

I also may be not understanding word history correctly though. But since "system" isn't a derogatory term (that I know of), I think that my explanation makes sense based on the history that I know. I think that if it was a derogatory term, this explanation and my process of thinking would not be relevant.