Current Consumption CD74HC4067 for battery powered application
Current per pin  and Total/Ground/VDD currents are basically thermal maximum limits set by the internal track widths connecting to the pins. At some point above this, you fuse/overheat something.

Not surprising when you think about how little aluminium there must be in the tracks on a chip.

I was surprised in a chip design that the tracks had to be bigger than the fets themselves to carry the current (in that particular process). Simple chips only have a few metal layers, and while process changes make the fets smaller, they don't change the resistance of aluminium