In researching App Pool Identities, I came across your question - late to the discussion but passing this on in case anyone else runs into it: the system doesn't create a user profile when using Application Pool Identity. According to Microsoft:

"However, with the switch to unique Application Pool identities, no user profile is created by the system. Only the standard application pools (DefaultAppPool and Classic .NET AppPool) have user profiles on disk. No user profile is created if the Administrator creates a new application pool."

Full documentation here: https://learn.microsoft.com/en-us/iis/manage/configuring-security/application-pool-identities#application-pool-identity-accounts