This mirrors my experience of SPN. I watched/read avidly through season 5. And I remember the "RPS is the high road" conversations in seasons 1 and 2, along with the ways in which wincest was written, pretty much exactly as you describe.

I did keep watching (purposefully a season or two behind what was airing), but I disengaged from the fandom itself pretty quickly when it moved to tumblr, and fundamentally became a place I no longer recognised.

Thanks for writing this up.