If abandoning their catalog distribution infrastructure on the eve of the Internet was Sears first foot in the grave, abandoning their exclusive house brands was the second. That started before the 1990s. And Radio Shack made the exact same mistake.
I'm old enough to remember walking into Sears stores in the 1950s and 60. Back then, you had full-line stores and hard-merchandise stores (no soft goods such as clothing). The latter eventually morphed into Sears Hardware, without the electronics and furniture. But whenever you walked into one, nearly everything was Sears-branded. And I mean EVERYTHING.
And not just Kenmore and Craftsman. I'm old enough to remember Silvertone audio products and Coldspot AC and refrigeration products. When you walked into the electronics department, you many have seen a couple national brands, but 90% was all Sears. Sears TVs and radios. Sears stereos. Even early Sears "pong" games and other gizmos. Sears bedding and whites. Sears clothing. I wore a couple Sears suits. Sears-branded boots. Even Sears-branded underwear. I have relatives with ancient Sears steel sheds still on their property (held up by the rust at this point).
Later. when you walked into the auto department, it was not just DieHard batteries. It was RoadHandler tires and Spectrum lubricants. In the early 1970s, nylon string lawn trimmers became the rage. And while Weed Eater was the leading national brand, Sears outsold them regularly with their "Weedwacker" brand, that eventually expanded into other "wackers" across the lawn and garden department, right next to the Sears-branded lawn food and weed killers.
And Sears spent decades and untold millions of dollars carefully cultivating these brands and sub-brands. In the early 70s, a commercial for an NFL game consisted of a DieHard commercial, followed by a RoadHandler commercial for winter. And Sears was the ONLY place you could buy these, and many other great products.
Sure, most of the stuff was made by someone else. Maybe White-Westinghouse or Whirlpool made it. But Sears was very careful to specify some additional styling, feature or specification to their product, nearly always something that made theirs a little extra, a little nicer. And always enough to differentiate it from the manufacturer's own product. Sears' products were unique then.
And when something had the gold "Sears Best" label on it, you knew you were getting a near top-of-market item that was well made and a fair value. I still have a "Sears Best" automotive tester and dwell station from the early 1970s, with that little gold seal on the box. Still works.
But the most important thing was you could only buy these things at Sears. They were unique. They had built an entire marketing universe of their unique products, with a complete monopoly on them. Oranges vs. apples, so no one else could really compete on price. When they gave them up, one by one, it turned the entire shopping experience into a price comparison. Because they are all just apples. There was no way they were going to compete on price with Walmart and the other modern "five and dimes" of the late Century. When they bought K-mart, they were acknowledging they had lost their biggest marketing advantage and were losing the price war, too.
And they "Service(d) what we sell". I always knew that whatever Sears product I bought, Sears would always have parts and service for it, conveniently. Sometimes for decades. Try walking up to a Walmart customer service desk to get your four year old LG TV repaired, and see what happens.
They gave up their competitive advantage, one they had spent decades building, and then died on the price battlefield. And they did it willingly. Again, complete executive management malpractice and a betrayal of an untold investment over generations.
Radio Shack did the exact same thing with their Realistic, Archer and Tandy brands and all the little sub-brands under them. The day RS started selling RCA-branded boom boxes in their stores, I know that they too had crossed the rubicon. There was no way that RS was going to successfully sell national brands against the Walmarts and Best Buys of the market. By the end, they were selling cell phones and expired batteries and a handful of odds and ends. All the old RS products were gone.