To me it sounds like human error. It happens, but staff aren’t the only ones able to spot an issue, you can too and by reporting a player it brings it to their attention and they can prioritize on it.
I doubt the staff would intentionally leave players saying disrespectful things alone. As for spam I think it is important to eliminate spam ASAP because it pollutes the chat making it hard for community fun and for the staff to pick up on other discrepancies, if they accidentally miss someone saying other bad things due to spam sure that sucks, but you can’t get them all. But like I said above, we the community can really help the staff if we report things.