Well, apart from the OEM violating the Android Compatibility Definition Document (CDD), failing the Compatibility Test Suite (CTS) and thus not getting their device Play-certified (so not being able to preload all the Google services, there is an economical impact as well:
As OEM you want Carriers to sell your device above everything else, because they are able to sell large volumes.
Carriers make money using network traffic, Google is paying Revenue-Share for ads to Carriers (and OEMs of certain size). Carriers measure this as part of the average revenue per user (ARPU).
--> The device would be designed to create less ARPU for the Carrier and Google and thus be less attractive for the entire ecosystem.
As OEM you want Carriers to sell your device above everything else, because they are able to sell large volumes.
Carriers make money using network traffic, Google is paying Revenue-Share for ads to Carriers (and OEMs of certain size). Carriers measure this as part of the average revenue per user (ARPU).
--> The device would be designed to create less ARPU for the Carrier and Google and thus be less attractive for the entire ecosystem.