The number of levels of traces and gates laid out is an important aspect of how much sophistication and capability available to connect ICs on a pcb. You are laying out power and ground and communication. There are lots of other considerations like the complexity of what you can plan to layout using software. But you stack layers of traces to add capability. More layers is naively more capability.

This article from Aug 2026 says 20 layers are for complex designs. https://www.pcbasic.com/blog/pcb-layers.html. So 124 layers looks like a huge increase.

Not my area, probably got it all wrong, hope this is useful.