In the case of #Wikipedia, though, printed copies should always offer &/or be accompanied with electronic copies. Wikipedia should really be under copyleft and it's not.
After all, paper printout is but a rudimentary form of DRM.
I'm not saying CC-BY-SA is useless and shouldn't exist, I'm saying there **is no** #copyleft in the CC license group. CC even used to encourage photographers license scaled versions CC-BY-SA & keep high quality images proprietary.
Cc: @cwebber @wikipedia @dos @dpk