If you want to learn more than what's covered by a guide (resp. this guide), diving through all the replies is a way to go. It may cover additional questions you might have, so you don't have to ask them (...again, for those who have answered them already). And it may cover advanced topics that weren't mentioned in the guide and you weren't thinking about at all until then. If the thread then consists of 60%+ chit chat * burying the useful bits, this is very tiring and devalues the thread which is supposed to be a guide.
* edit: and repeatedly asked questions because people don't feel like searching 200 pages, just like below