Here is a situation.
I am not sure you guys know it or not.
Before, many seller list BIN item with lower price and higher shipping. Like 50+ 50 instead of 90 + 10
In this case, buyer still pay 100. Seller pay less in the final fee. Plus when buyer serch items by price, it comes first.
So ebay looses money.
In order to change it, they start DSR.
And they want have more final fee charge, even want the shipping part.
So, they nicely suggest " you can quickly increase the DSR by free shipping" which lead to adding shipping to the final price.
This is what they want.