How does it hurt investment? Those tiny nations are only helping eliminate an inefficient form of taxation. The main problem is that only multinationals can make use of it.
Hiding huge amounts of money in tax havens is actively detrimental to the economy. I believe the goal of any economy should be to better our lives, not hoard wealth and sit on it.
Without taxation, the infrastructures needed to maintain a healthy economy are unsustainable. We need to ensure that what companies benefit from public services is taken back so it can be reinvested.
Money is not "hidden" or "hoarded" in tax havens, nor does hoarding money affect the economy negatively. Taxation is necessary for infrastructure (though that is actually a small fraction: about 3% of US federal taxes goes to infrastructure), and I did not say or imply that taxation is unnecessary. The question of what the best level of taxation is, and what the best place to levy those taxes is, cannot be decided based on high level slogans. One thing is clear though: standardizing tax rates is bad because it removes the competitive aspect between countries. It is good if people and companies are able to move to the places that give them the best public services for the least cost, for the same reason that it is good that salaries are not standardized between companies, and the same reason why it is good that airline ticket prices are no longer standardized by the IATA and CAB.