I read frequent complaints about poloniex freezing customers' funds.
Can you justify it?
They may have been good when they were new, but at least since I joined here 9 months and 2 days ago they are bad.
Did the bitshares blockchain ever have any other purpose other than for decentralized exchange?
They do disable withdrawals often, that's true.
All of their main functions are basically exchange-related. Their most important product is BitUSD, the oldest and arguably best stablecoin in existence. It's been tracking the value of the US dollar continuously since late 2014.