Good to see those wholly unconnected with Tax Justice Network find the argument that tax havens help keep tax rates down absolutely absurd.
Tax havens / secrecy jurisdictions promote criminal activity. If they did not they would not need the secrecy.
That's about the beginning and the end of it.
If they mean, as they say, that they do not want to encourage tax evasion then remove the secrecy. If they won't the conclusion is obvious: they're not telling the truth.