I always find those kinds of conversations useful, provided they are clearly presented in context. The deeper my relationship with a piece of software gets the more I find myself running into questions that can best be answered by conversations that were had many years previously, against much older versions of the software. I'd love to see the old mailing list content available online in an archive that includes a prominent "Warning: this conversation from 2009 relates to a 12 year old version of the software" warning, rather than leaving that content entirely unavailable.