We use commas to separate items in a list, to identify an aside remark, and between certain words, such as city and state. Here’s another use.
Sometimes you need a pause, especially when you represent spoken English, even when you have no grammatical requirement to do so. In fact, you can use this physical pause function even when it would otherwise be incorrect to use a comma:
In fact, the cartoonist added a line break to emphasize the pause! I even used this technique on a post I shared a couple months ago.
Ordinarily you are incorrect to separate a subject and its verb with a single comma, so when you use this technique, be sure you know what you’re doing.