Is poloniex now copying yobit... they have been doing this for years.
Look at vanilla coin
It's double the price on bittrex??
Same for lots of coins frozen in wallets on polo.
It seems yes, they are copying yobit. Hard to find good altcoin exchange service, mostly they aim to freeze accounts and get rid of some profit loss.
Yeah I wonder what is the point of random freezing and not allowing to trade certain coins. I didn't had any major problems with polo but as I am hearing it makes me think twice when using it.
Important thing to remember is that you should not use exchanges as wallets. Things can get buggy, something will go wrong with time maybe hack, maybe it will go Gox so better safe than sorry.
To stop loss and remain profit, that's main idea. They don't do this on everyone because it will be like a scam and they don't want it. Also everything depends on exchangers, I think we can trust some exchangers with our bitcoins ( not with 100btc ). Some legit and licensed exchangers won't freeze your account unless they see there are some wrong activities here (for example send money in casino's adress and etc).