The biggest mistake Sears Kmart made was not staying current. IOW they should have adopted the Amazon model of online sales.
Sears was pretty far gone before there was such a thing as online sales. I thought ending their catalog business and going to retail outlets only was a huge mistake. If Sears had kept its catalog business going until the internet came along, there might never have been an Amazon. They'd have been positioned to just move catalog sales to the internet.
Sears had the Wishbook, a massive catalog. It was going online but mismanagement ended it in the 1990’s.
Sears did have an online presence. It was called “shop your way”. I think it’s still around. I used to buy a lot stoves and ovens from them. It was the best prices I could find. Order online and pick up at the store when they came in. Got a lot of points too for my Christmas shopping.
I miss the hoggie sandwiches at Kmart.