That's why.
Here's a pic of my kettle, same one as in post #5 above. You can see the various items on ports; lower left is a ball valve on the "out" port, connected to a dip tube on the inside of the kettle. The port on the lower right is a temp probe to connect to my panel. The port in the middle is the recirculation port.
Different brewers do this differently, but in my case I draw wort out of the "out" port into my pump; from the pump, into my counterflow chiller; from the counterflow chiller back to the recirculation port. When it's time to move that wort into the fermenter, I shut off the pump; close the recirculation port ball valve, use a forceps to clamp the hose right at the camlock connector, then disconnect from the recirc port and connect to the fermenter.
I have a Spike CF10 and I fill it through the racking port, the wort comes out through the racking arm on the inside of the fermenter.
If I couldn't shut off the recirc port, it'd be a mess.
BTW, here are the forceps I use to clamp off the silicone hoses:
https://www.amazon.com/Excel-Tube-O...+occluding+clamp&qid=1589459346&s=hpc&sr=8-15
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