What’s the meaning of “resources external to the SQL Server computer are needed” in Microsoft’s SQL documentation?


In Microsoft’s SQL Server documentation on Windows service account configuration, the decision to use either a VA (virtual account) or a MSA (managed service account) hinges on whether

resources external to the SQL Server computer are needed

What exactly does this phrase mean here? I’m seeking an explanation that makes sense to an ‘accidental DBA’ with minimal experience of SQL Server, or Windows Server, configuration. What counts as a ‘resource’ here, and what kinds of ‘need’ are relevant?

Context: I have a fresh SQL Server 2019 VM on Azure, which was configured with VAs out-of-the-box, and I’m trying to decide whether we need to switch to using MSAs. I have found multiple other questions concerning this same documentation page and/or the same basic decision between VAs or MSAs (or regular AD Accounts) – but none really explain this specific phrase in a way that helps me apply it to my particular scenario. Which is essentially a data warehouse use-case: data will be coming into this SQL instance from external sources, but that’ll be managed by a third-party DW automation application running SSIS scripts, not directly by the SQL engine. (This application has its own AD service accounts.)

Whilst I’ve explained my specific scenario here to try to clarify the question, I’m keen for a generic answer so anyone with any SQL Server use case can evaluate this "resources external to the SQL Server" phrase for their needs. Specific answers for my use case are also welcome.