This would effectly add the command "Set-StrictMode -version 5" at the beginning of the scriptblock.
The reason why should should be a parameter vs just having the user add that line to every script is that it allows someone to set this via $PSDefaultParameterValues and have it affect an entire corpus of scripts (without having to change the scripts itself).

Here is the workaround that I wrote to implement this:
https://www.powershellgallery.com/packages/Invoke-Command