This is not a question regarding which is better; I am purely interested in use cases where PowerShell cannot perform the same functions that CMD can.
The only thing that comes to mind for me is that batch files will essentially run in any Windows environment; the user double clicks a batch file or calls it from another program and it executes.
With PowerShell scripts, as far as I know, you can't simply click them to run. To provide similar functionality, you would need to wrap the execution of the script in a batch file or something:
powershell.exe -Command fileName.ps1 or powershell.exe -executionpolicy remotesigned -File fileName.ps1
This post pretty much says PowerShell can do everything CMD can do and more, although PowerShell (as of 3 years ago) doesn't support symbolic links.
I also saw a reddit post that had a question regarding a homework assignment which involved writing a batch script. Is CMD still being actively taught in schools?