One of the problems with understanding the culture in Ancient Crete is that we are limited to archaeological discoveries. We have not deciphered Linear A and so the writings, that might explain unknowns about this civilization cannot be read. That means that many facts, about their diet for example – did they have cheese? -, about their political structure – was there a King or was it a theocracy-, or about whether this society was an empire or a loose confederation of city states, are unknown.
We know there were colonies spread out over the Aegean. Akrotiri, buried in ash and currently being excavated, is one. But were they just colonies or independent city states?
On Crete, other cities besides Knossos, arguably the largest and best known, were wealthy and powerful. Gortyna was one and it is thought there was conflict between the two cities. That seems to imply equally powerful city states – but we don’t know.
I’ve read arguments on both sides of the debate and both seem equally plausible to me.