If you leave them plugged in, they'll squirt out a little ink to prevent said clogging of the head. This is much more economical than washing dried ink residue out with loads of fresh ink.
I have a Brother with a similar approach. It has ink tanks with huge capacity and it powers up once a day to do something which I presume is keeping the heads clear.
It frightened the crap out of me once but I'm used to it now.
It frightened the crap out of me once but I'm used to it now.