Is the motherboard built around the CPU?(theoretical question)

[principiantehardware]

I am going to try to explain this with an example. When I access to a CPU, for example, Intel Core i7-6700 Processor:

• 
  * Memory Specifications:
  • 
    -Memory Types: DDR4-1866/2133, DDR3L-1333/1600 @ 1.35V

• 
  * Expansion Options:
  • 
    -PCI Express Configuration: Up to 1x16, 2x8, 1x8+2x4

• 
  * Package Specifications:
  • 
    -Sockets Supported: FCLGA1151

(Source: Intel)

So, motherboard manufacturers know when they have to build a motherboard with Socket: FCLGA1151 must know that they have to build MAXIMUN: 1x16, 2x8, 1x8+2x4 of PCI Express lane, for example.

So, all motherboards are build according to CPU generation/type/etc. Am I right?

 

[smorizio]

no. not quite right.

it starts out from years ago mb start by size and or type. old old mb with at mb the new mb are atx for factor.
there full size. micro and itx. with each cpu they have to be mached up to north/southbridge chipset.
most new mb use one chip as both.
http://cdn.arstechnica.net/wp-content/uploads/sites/3/2015/08/skylake-slide-block-diagram-ish.png
aib then have to make the mb to cpu and chipset vendor spec.