I have never really understod the Dutch Auction logistics, but I understand them to work as you just pointed out.
I cant think of one reason to do a dutch auction!
The only time I think it would a huge benefit would be if you had lots of the same item. Then you would save on listing fee's I guess and 1 bidder may buy a stack of them.
I never use them personally, I list my multiple items one at a time.
Lexie