I thought we were way past the "bigger brain means more intelligence" stage of neuroscience?

Bigger brain does not automatically mean more intelligence, but we have reasons to suspect that homo neanderthalensis may have been more intelligent than contemporary homo sapiens other than bigger brains.

All data shows there's a moderate correlation.

You can't draw conclusions on individuals, but at a species level bigger brain, especially compared to body size, strongly correlates with intelligence

Even neuronal density is simplistic, and the dimension of size alone doesn't consider that.