The idea of an "increase" in the nobility doesn't really hold up to close scrutiny. Nor do the theories about "hyper warfare" and resource depletion.

If you go back to the earliest "pre-classic" sites like El Mirador or the newly discovered (2020) Aguada Fénix (Tabasco, Mexico) then you are talking about 1,000 to 800 BC.

By 800AD the Maya had been flourishing for at least 1,600 years.

Societies that have been going strong for 1,600+ years don't generally "completely collapse" virtually overnight. Usually there is a MASSIVE external stressor that pushes them over the edge.

The collapse of "Old Kingdom" Egypt is analogous. After several thousand years of stability the climate turned sour, famine stalked the land, and the old dynasties fell.