Yea how many people delete source content after they've uploaded. I wouldn't be surprised a lot of people do that. General population doesn't think it's worth to simply buy more space either online or on disk. It can be expensive to do so even for people like me who realize that disk on the whole is cheap compared to losing the data.

That isn't the point. It is published in spot. The amount of breakage between SC going down and that art being uploaded to a new site ... at most I would think 10% or less would make the transition.