More to the point, I'm fine with "the Jedi didn't have the power to do anything about slavery on Tatooine" as long as it's taken to its logical conclusion--i.e., Obi-Wan's thing about "the Jedi Knights were the guardians of peace and justice" is essentially posturing, for most of the galaxy the problem with the Empire was entirely about the active presence of the Empire and not the lack of presence of the Jedi, and Obi-Wan is being singularly self-absorbed when he ties the murder of the Jedi Order directly to "the dark times."