One thing is strange. Mostly, they are newcomers and people with little money they generally say that Poloniex is a scam. When I read the forums, I almost will not find anyone who would have blocked a larger amount of money.
There are complaints about larger amounts too, but I am not convinced.
I think that we have 2 things here: internal issues at Polo, but not as many as some wants us believe and a campaign against Polo, since they became too big and may have upset somebody...
I wish the internal issues get fixed though, they should afford that..