[usrn]

I'd imagine power shell has some way to pull the available parameters out of cmdlets (they probably all inherit from some cmdlet class or something.) On bash you have to get this from somewhere else.

[behnamoh]

I think it also helps that PowerShell treats everything as objects and can pass them in pipes.

[usrn]

If bash had some way to specify that a command is "pure" (doesn't mutate anything) you could do this there (among other nice things.)