I think there are a lot of factors here.
We know from research that whistle-blowing doesn't take place in some organizations because there's such an open environment and competent management. When wrongdoing is reported to your boss, it just gets dealt with and there are no repercussions. It's not even called whistle-blowing.
In an environment that's very hierarchical, where there's a fear to report any bad news upwards and there's a significant amount of harassment existing as a problem, then whistle-blowing mechanisms are required. They are not going to fix this, but they will help to avoid some of the harm because whistle-blowing can act as an early warning and prevent major problems from spiralling out of control.
There's no reason in the world that Phoenix should have lasted beyond the first year of its operation, yet it went on for years and was ultimately released. It's mind-boggling.
On the larger picture of the atmosphere in the public service, I have opinions, but I don't have direct experience, so I'll pass—