It's possible that the mixed media option is part the reason for the high overlap, but I'll need to look at previous years' signup data to know. There's also a social circle effect - both are smallish exchanges, and all it takes is one person doing both and having fun, and two years later you get this sort of an overlap through word-of-mouth.

(Also, somewhat off-topping: I'm modding purimgifts as of this year. If you want to, you're absolutely welcome - encouraged, even - to contact me however is good for you [PM, the purimgifts mod email] and explain what was stressful to you about purimgifts. There's one factor I know was a problem - the last-minute-y schedule - and addressing that issue is one of the key reasons I was added to the team. But if there's anything more, I really do want to know.)