A comma can be used to improve readability, but it can also indicate a pause while talking. I feel a pause after “and that” is as common as no pause. That said, I cannot know if that was the poster’s intent; it’s only my interpretation of the usage.

The “rules” of a language describe how people use the language, but those conventions are subject to constant change because communication is a collaborative art. Some might say it’s better to use a semicolon rather than a comma, for example.

I feel like any linguist upset by non-prescriptive language needs to maybe reconsider their life choices. Imagine telling someone they’re painting incorrectly or being mad at the discovery of a new species.

You leave the stroller for a moment to grab your take-away order and come back to a crow repeatedly attempting to insert a still-living snail into the baby’s face. The snail is confused, but calm. The crow is frustrated. The baby won’t stop screaming, further frustrating the crow. Just eat the snail, idiot.

You have to say that on Meta if you want them to read it.