permission regarding the sql server service account use in always on

hi tech friends,

like to clarify is it necessary to grant the sql server service account administrator rights? I am abit confuse, it seem to be needed. i google a few blogs and it seem others also mention to grant this account a local administrator rights. I am setting up a alwaysON sql server. Understand that under normal standalone or traditional fcl, the account no need any administrator rights.

Permissions (Server Instance)

Enabling AlwaysOn Availability Groups

Requires membership in the Administrator group on the local computer and full control on the WSFC cluster.