My first thought: Why does it have to be an argument? If someone wants to write deep, well-researched, original biographies for US Presidents, why not encourage them? Or if someone wants to dig into serious genealogical lineages, why not encourage that too?
Of course, that evades the question. It's a legitimate thing to discuss when a project like the US Presidents group is discussing what they should focus their limited efforts on. And it's also good to have standards and recommendations, especially concerning the style of biographies.
Regarding the biographies, I never see a reason to duplicate what's written elsewhere. If it's public domain it's legal to duplicate it, but why? Why not just link to the other website? Judicious excerpts might make sense, so that we can at least include a quick biographical overview, but wholesale duplication doesn't make sense to me.