Its true you dont have to run the same strength nutrients with autopots as you do top feeding.
Theres no reason to “reset the medium” with autopots, its hydroponics, once the medium established its good to go 
But only time I’ve ever seen an autopot need flushed is because the grower was also adding things in the top 
Im not saying it can’t happen, but if it does, I’d bet money it could have been prevented with a better understanding of how autopots work.
Check out the plants I grow with my autopots useing GH 1 part nutrients at about half strength of what’s normally used. My ppm is rarely over 600 in my reservoir in flower, my plants veg around 400ppm.
That’s another advantage of bottom feeding, no waisted water or nutrients as everything is consumed as the plants need it…
I did very well top feeding but I do way better now that I’ve learned these autopots. No way I’d dobit any other way now…