How is an individual capable of abusing Xbox's enforcement system so effectively for such a...

Hello Mookachalupa. My name is Jose. An independent advisor.

Please note that this is a Microsoft public forum, where we are gamers like you trying to guide/help other gamers solve basic problems they are having, this means we are not Microsoft employees so we do not have access to accounts nor to user data. .

But I can tell you this.

The control system is complex. The Xbox control system is a complex system that requires a large amount of data to function. This can make it difficult for Microsoft to identify cases of abuse.

Microsoft is a large company, but it has limited resources. This can make it difficult for Microsoft to investigate and address all cases of abuse.

Therefore, Microsoft is aware of this and is therefore working to improve the Xbox control system to make it more difficult for malicious users to abuse the system. However, there are always likely to be some cases of abuse that go unnoticed.

Keep insisting, don't give up.

I believe you are correct. It use to just be a means of other players to have a sense of how you are as an individual, and now serves to weed out the toxic players. Unfortunately no system can be perfect and there is always potential for abuse unfortunately.
All I think you can do is report and abuse and be able to document it with screenshots, etc. and contact enforcement.

Furthermore, the reason that this is serious is because of the effects it can have on individuals.

“emotional and verbal abuse can have short-term and long-lasting effects that are just as serious as the effects of physical abuse. Emotional and verbal abuse includes insults and attempts to scare, isolate, or control you. It is also often a sign
that physical abuse may follow. Emotional and verbal abuse may also continue if physical abuse starts. If you have been abused, it is never your fault.” -womenshealth.gov

https://www.womenshealth.gov/relationships-and-safety/other-types/emotional-and-verbal-abuse

When you open each individual message on Xbox One, you have the option there to report the other player. You can do this for each message that you feel is abusive.

This will then be looked into by the Xbox Live Enforcement team and they will take appropriate action, either by blocking communications or suspending their gold privileges. Depending on the number of previous offences and how abusive the messages are will
contribute to the length/type of ban.

The system was abused by one individual posting filth.

As in life everyone has to suffer for the actions of the few.