Is there any advantage to adding a networked streamer to a Sonos Speaker Systems?

Now I am confused.  If the Sonos App is a networked streamer then why do they offer the Sonos Port which is a network streamer?

https://www.sonos.com/en-us/shop/port

The port is there so you can add a CD player, Turntable or any other Line in input.  It then streams that to your Sonos Network.  Later speakers such as the Era 300 and 100 can also do the same thing as a port but for less.

But you can use the Sonos app to stream nearly any On line music streaming service service to play from any or all of your speakers.

If you click the link you posted, it says:

Bring the Sonos experience to your existing stereo or receiver, and enjoy endless possibilities for multiroom listening

Connect Port to your traditional audio equipment to stream music, radio, audiobooks, and more from all your favorite services. Control is easy with the Sonos app and Apple AirPlay 2. Expand your sound system any time by adding Sonos speakers around your home. Everything works

The Sonos App is not a ‘networked streamer’ its used to control the Sonos System.

All Sonos devices (the App is just a controller) are “networked streamers” in that they can stream sources from your network and/or the internet.  The Port is a network streamer you can use with traditional audio equipment like a receiver or amp/preamp combo.