Ah, yes, findstr and its plethora of problems and fun :D. One of the top answerers for batch files on Stack Overflow took the time of piecing together all sorts of undocumented things, limitations and shortcomings of findstr: stackoverflow.com/.../73070
And indeed, PowerShell is probably the reason why there is little need of building better batch file tools. Although I rarely found the need of using Select-String. (Get-Content foo) -match '...' works just as well and I don't have to remember the arguments to Select-String ;-)