Not really a purge.

You could call it a purge if they "purged" all coins from the bank, but not just blocking a function.
The trading is a huge issue tho. Everybody with a decent amount of coins could just gift every new user enough to buy Members+ and many actually did this.
Even I could gift 2,000 users per day a Members+ without making any "loss", but that would be completely contrary to the purpose of the system.
Yes, the contests belong in this category too, because in the end, you receive coins at the pleasure of a user and thus defeat the point of the coin system.
But there is a solution for this. Dunno if this would work, but mods could grand some selected users, who have proven to be trustworthy a "Coin-Trading-Pass", so they can hold contests and gift coins for it.