TLDR: the language used to talk about science isn't the same as common day to day language.

Long explanation:

It's a neurotransmitter...

It exists to do something.

If for one reason or another that's not happening, or just too much or too less, then the biological process is not functioning correctly.

We're not talking about if that's a good or bad thing.

Like, I don't have a specific liver enzyme that breaks opioids down into active metabolites. It's nonfunctioning.

But that's a good thing, because the trade off to common opioids not working, is better to me than the opposite where I'm incredibly likely to get addictied from metabolizing too fast.

If oxytocin isn't able to work, then something in the process isn't functioning correctly. That's not a judgement on what's normal or best. It's a factual statement about a biological process. One part might not work at all, both parts might not, or you might just be on different ends of a couple different scales.

Or like pheromones. Humans can produce very small amounts, we just don't have the organ to pick it up. It's a system where it's 100% for it to be non functional.

That's kind of how evolution ebbs and flows. Sometimes stuff just stops working if there's no pressure for it.