Every kind of language has rules

Yes, even the ones that you don’t like. Here’s a quote from Spoken Soul by John Russell Rickford and Russell John Rickford (2000: 92). It’s perfect in expressing the point that all language varieties have rules:

Every human language studied to date – whether loved or hated, prestigious or not – has regularities or rules of this type [i.e. conventional and systematic ways of pronouncing, modifying, and combining words]. A moment’s reflection would show why this is so. Without regularities, a language variety could not be successfully acquired or used in everyday life, and this applies to Spoken Soul, or Ebonics, as much as to the “Received Pronunciation,” or “BBC English,” of the British upper crust. Characterizations of the former as careless or lazy, and of the latter as careful or refined, are subjective social and political evaluations that reflect prejudices and preconceptions about the people who usually speak each variety.

That is so good. The book that it appears in is about Black English (also called African American Vernacular English), so of course Rickford and Rickford had to address the (uninformed) idea that Black English is just “English without rules.” It’s not and it never was.

You don’t get to claim that some specific group(s) of people don’t have any rules to the way they speak. Because if you claim that, it will say more about your judgment of those people than it will about your assessment of their language. (Well, it will also say that you’re not very good at making assessments about language.)

Every language variety follows systematic rules. Every single one. Not some. Not most. All of them. They may not follow the same rules as each other, but they follow rules nonetheless.

A tired English “rule”

Here’s a good example of why we split infinitives in English:

You may have heard that it’s bad grammar to split an infinitive. This is a made up rule that was taken directly from Latin. Thankfully, it seems to have been buried for good as people are starting to realize it’s a ridiculous rule. The infinitive is already split in English – there’s always a space between to and the verb. And you can see here that following the rule would produce some really weird sentences:

I wonder what it feels like to be not tired.

I wonder what it feels like not to be tired.

Both of those sound unnatural and unindiomatic.