On Unix you can do pretty much whatever you want as long as "whatever I want" can be represented by a string of text. In PS you get to work with objects. PS is more like a Python shell than bash.
If you want, your PS commandlets can return strings as well, so it's not like every part of your pipeline has to be in PS either.
Cumbersome. To create my own cmdlet that does the cool stuff Powershell can do (as far as piping) my choices are a terrible language like ps1 or .NET.
On Unix I can use pretty much whatever I want because the shell isn't tied to a specific runtime.