User logon certificate in personal key store

I'm currently evaluating the use of smartcard logon (PIV) for my Windows clients. Some smartcard vendors, and also https://learn.microsoft.com/en-us/troubleshoot/windows-server/windows-security/enabling-smart-card-logon-third-party-certification-authorities (step 8), suggest to import the user certificate into the personal key store of the user. My certificate is only for user logon. For me the user logon also works without importing the certificate. What are the advantages or disadvantages of importing the certificate?