I think that in the early days folk would come in and get a gig or two for free when their key market is the movie industry that really needs and makes use of those huge files. and can afford good money to do so. Second Life manages with much smaller 1024x1024 max texture files and suddenly there is a million folk scouring the internet for textures that even the very successful make hundreds of dollars a month, and most not even break even. That is why they set up the limits.
Later Second Life and the other grids demanded rights on their TOS in what I think was Lawyer absurdity because they could get away with it. However CG Textures (as was their name then) shut everyone off from their stuff saying it could not be used in the grids, but that which was downloaded under the old rules was still under the old rules. I had a huge collection so did not go back there as I wanted to keep selling in the grids,
So now I am doing actual stuff instead of virtual and inquired as to what the rules were for this and got a green light as long as the links to the textures were passed about and not the textures themselves, so with that go ahead I passed the information here. 