There is nothing wrong with them having a beneficial tax system if it means people will relocate and spend money there while paying (some) tax.
What does a country like Malta, Cyprus or Monaco honestly have to lose by being a tax haven?
Simplisticly speaking, they only gain from being tax havens. Point is that everyone else looses. Taxing is a zero-sum situation where if you pay taxes in one place, you don't pay them somewhere else. So this is a nonsensical, because essentially the other countries' taxes are rendered optional. Why pay the whole thing, when you can do some corporate gymnastics and pay less to a tax haven?
It comes down to what in the socialist context is referred to as solidarity. In this case, if you want to tax something, everyone has to agree to that. If there are notable exceptions, it doesn't work. Malta is an example of a notable exception.
And Singapore is not as majority are Chinese/china culture
Especially the newer EU member states that have been experiencing an incredible amount of brain-drain i.e. people moving to bigger/"richer" countries. Bigger countries profit from that while smaller die out - unless they make themselves more attractive somehow. To some extent its happening within bigger countries as well with urbanisation - in Germany for example villages that are not close to bigger urban centres have the same problem.
Whether you call it a "tax haven" or subsidising - in practice its virtually the same thing. Of course you need some rules in place to prevent creative tax practices by multinationals (like linking taxation to physical presence) - but its a do or die sort of thing.