Basically
Let's start with some basics:
"Okay, so I read it, but I am not sure what message he is trying to put across. What is his purpose? Please help!"
It's a whimsical piece that points out a stereotype he believes most people hold about poets. Unlike more straightforward literature, the purpose is only revealed at the end: "It is the assumption that the poet is..." One could speculate that he does this to mirror what is typically a poetic design and therefore ironically hyperbolize the whole thing. He spends a lot of time describing poetic little details, like his "long, soft hair," and his "delicate face." He dances around a tedious description of a pathetic man only to finally say that this stereotype is inaccurate. It's a funny little "poets are people too" campaign.