You are correct, there is no Set-VMAdvancedConfiguration cmdlet in PowerCLI.
But the fact that you write a function, adn use it as you would a builtin cmdlet, is imho one of the nice features of PowerShell.
You can extend the language in many ways and reuse the functions you, or someone else, writes.
This modularity, and the fact that you don't really need to know what goes on inside a function, makes PowerShell a real plug-and-play language.
As William shows in his post, you can easily do this (call the Set-VMAdvancedConfiguration function) for just 1 VM (you control that with the Get-VM cmdlet).
There is no need to do this immediatly for your complete vSphere environment.