In my case, they were telling me at first that I couldn't register the same game on multiple accounts under the same family account.
I objected, because I seriously thought that was the whole POINT of having family accounts.
They finally relented, except that my additional accounts (two) were each registered with my own info (birthday, etc.) - they said that I needed to have actual family members listed.
What irks me the most is that there are folks who cheat the system, buy/sell/trade codes, steal them from GameStop/Rental stores, etc.,etc. There was even a douche on CAG who was talking about buying a 3DS, registering it, then returning it just so he could get platinum this year. There are other folks who set up many, many non-family accounts so they can score tons of the platinum prizes each year.
Meanwhile, I legitimately purchase tons of stuff and don't cheat the system... and I get the kabosh because I write in regarding coins I got gypped out of?
What happened - apparently the new coin values didn't switch over immediately (wish I had known that on July 1st when I registered a crap ton of stuff!). Not a huge problem, but I registered 11 3DS titles that went from 30 coins to 40 coins.. but only got the 30 coin value for them. So, I wrote in asking for my 110 coins.