Also, perhaps standardization could play a role. If the Redis / Mongo / etc were standardized by a neutral party, it may make it riskier for big techs to make

Also, perhaps standardization could play a role. If the Redis / Mongo / etc were standardized by a neutral party, it may make it riskier for big techs to make their on proprietary or incompatible modifications. Though I guess this doesn't apply too much to postgresql, since any serious RDBMS is much more than just SQL standards compliant.