These areas form something later rhetoricians have labeled the Rhetorical Triangle.
Advertisements do it all the time.
Perhaps a writer will offer an anecdote to illustrate suffering or appeal to readers as parents concerned for their children. Effective arguments will probably include facts and other supporting details to back up the author's claims. They may contain testimony from authorities and will demonstrate the writer's carefulness in choosing and considering evidence. Again, the equal sides and angles illustrate the concept that each appeal is as important as the others. Too much of one is likely to produce an argument that readers will either find unconvincing or, worse yet, cause them to stop reading.