Smart people don't use force to get paid. They usually obtain a pay rise through offering a better product,not through extortion scams (public sector workers striking).
They are allowed to bargain, or negotiate what ever you want to call it, this is a fair tool. A major problem is that these agencies aren't paying what top talent requires. So people are underpaid and also, other people that could do really important work go else where and use their intelligence on advertising.