Sorry but people who weren’t even staff when the refund system was implemented shouldn’t be discussing it’s “intended design” and claiming people are exploiting it, you say “we” but you did not develop or implement it originally so don’t group yourself with the people who actually did and try to speak on their behalf.
The intended design of the refund system was to refund an upload and return half of the Gralats, it does not matter what they use the Gralats for. The quote for exploit you provided literally says that exploit is the use of a bug/glitch, but all they did was use an intended feature.
It wasn’t patched for years because there is nothing to patch, you guys want to change it now which is fine and actually something I agree with, but don’t try to act like it was a broken system that was being exploited.