>>308143
Because it's not actually a comic, but usually a self-insert of their idea vs strawman of what they don't agree with. If they put that just in text, it's much easier to ignore them (especially when it's something fucking stupid, like a six-year lecturing an adult on transgender issues). By prettying it up and adding a little character to spout the words, they can pass it off as commentary comic instead of a blog post. The reason why there's text walls is usually because the people that stick political and modern commentary in web comics aren't trying to make it a part of the comic, but make the comic a part of their commentary. They don't start with a comic and add the text, they already have their textwall readied before the pencil even has the paper.
Really, all of this is done in the small hope that the average reader will take their position a little more seriously just because of their art, and that's probably the number one benefit to inserting a wall of text in a comic instead of just posting your thoughts as is.
Take the comic posted here as an example (this is an edit, but the main argument hasn't been altered): It's a comic about a girl lecturing a guy about what women want. But if you knew the author (a guy) and he sperged out about what women want, you'd think he was an idiot, especially if you were a woman. A comic helps mask the fact that this man considers himself the end authority on what women like. That's the benefit of a comic- you get to hide your ideas and critics behind mouthpieces and strawmen, and alter each one in the hopes that you'll seem just a tad less retarded.
Minority disagrees with you about a minority issue? Draw your self-insert as a minority and your critic as a white person, and sudden, it doesn't seem like you're wrong at all. Somebody disagrees with you on something related to women? Draw a female character representing your thoughts, and make your critic a (probably white) neckbeard male. (Just like this example.)
It also helps mask your identity towards third parties that don't know you at all. Someone unfamiliar with this artist might think they have some semblance of a point, and leave it at that, because who knows every author of media they read on the internet? Or has the time to? But someone who is familiar with the artist is already going to be skeptical because he's the same guy that regularly drops his spaghetti about children's toys and gets into an internet slapfight roughly once a month over stupid shit.