How pervasive it is depends on how scare resources are. From my experience as resources get scarce humans group up together by a one or more of the common properties they share.

Race, religion, county of origin, urban or rural, sexuality, union or scab, favorite sports team, etc

I don't see why educational attainment is any different. The only part that is missing in the software industry is a scarcity of resources and the shift described in the grandparent comment and those behaviors will happen at scale.