[majormajor]

Centralization of people into cities led to many, many, many historical advancements in arts and sciences.

Decentralization of cities - competition - sometimes helps even more, but the societies that never centralized never got as far. (And that decentralization can backfire sometimes too, e.g. military competition instead of economic.)

[int_19h]

Societies that never centralized didn't get far mainly because they were conquered by the societies that did. But I don't think it's reasonable to consider that an advantage of centralization - it's more that it turns out to be such a huge disadvantage, it spills over to your neighbors even if they don't like it.