You misunderstand what Billy Gates said. Windows sets a very restricted execution policy in PowerShell by default. It doesn't matter whether your systems are domain joined or not. In addition, PowerShell does not run with elevated privileges unless you explicitly tell it to (right-click > Run as Administrator).
As far as I can tell, these scripts cannot affect the average user because they would be blocked both by the default execution policy (cannot run unsigned scripts from external sources) and by the lack of elevated privileges to make system changes.