In context of https://jira.hl7.org/browse/FHIR-28375 we propose that service provider is the better attribute to be Must Support rather than location. 

We note that the service provider is more important.  There is a bigger need to obtain the organization responsible, which is the .serviceProvider. We recognize that for home visits the home location would be relevant, but not every system documents home or school visits while the serviceProvider would be clear and relevant.  If we only have location for those visits, as .location.managingOrganization would be irrelevant, we do not know who is responsible and can be contacted as needed.  Knowing who is responsible is more critical, hence .serviceProvider should be Must Support, and use US Core Organization Profile as the reference, while .location should be optional.

Links to pages:

https://build.fhir.org/ig/HL7/US-Core-R4/StructureDefinition-us-core-encounter.html

https://build.fhir.org/ig/HL7/US-Core-R4/StructureDefinition-us-core-encounter.html