If you have no constraints on capital flow, then you can attack currencies freely.
That creates what international economists sometimes call a virtual parliament of investors and lenders who can - I'm quoting from technical literature - "carry out a moment by moment referrendum on government policies". And if they think the policies are irrational, they can vote against them by capital flight or by attacks on the currencies, and so on. Policies that are irrational are, by definition, those that benefit people, but don't improve profit and market access and so on. And therefore, governments face what's called a dual constituency - their own population, and the virtual parliament.
And the virtual parliament usually wins, especially in poorer countries. The rich countries, it was modulated, they didn't accept the neo-liberal package as completely as say, Latin America, but to the extent that they did, the effects are predictable. And the same is true of other elements of neo-liberal programs. Take say, privitization, which became a mantra. Well, by definition, privitization undercuts democracy. It takes something out of the public arena and puts it into the hands of unaccountable private tyrannies that are created and appointed by the state, which is what corporations are.