I am not missing the scope of the argument. The commenter acknowledged that language rules and accepted uses exist, and simply argued that they change. You distorted that into the idea that anyone can introduce any change at any time and expect that it will be accepted. I objected to that distortion.

If you truly don't understand why it is a distortion and are genuinely interested in understanding what language change is, how it occurs and what legitimizes it, I encourage you to do some research as it is a really interesting topic. Here are a few short, free, good quality and relevant sources that I just found in a quick search:

Is English Changing? - an article from the Linguistic Society of America, very interesting and readable

Language change - a somewhat dry Wikipedia article that gives a good explanation of the actual mechanisms of language change.

How are the standards of English language changing? - a short video

Usage (language)) - Wikipedia article that also explains the difference between descriptive and prescriptive approaches to language

Style guide - a Wikipedia article about style guides and their purpose and application