Generally, private sellers who are selling their own secondhand items, don't have a replacement to offer.
Business sellers, who are selling multiples of brand new items, don't have to use Simple Delivery.
So, in my opinion, Ebay have thought it through.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)