What is the purpose of the long passages in the chapter describing the Grangerford hosue?

Twain offers social commentary in three separate escapades in the novel. One revolves around the Grangerford and Shepherdson families participating in a violent, tragic feud. Huck explains how civilized, wealthy and respected the Grangerford family is, but then shatters this image by detailing the feud's excessive and tragic killings. Here, Twain demonstrates the utter stupidity of even the most educated and respected families, who can destroy themselves through nonsensical behavior and excessive pride. The house provides a commentary about how wealth doesn't always amount to common sense.