The march towards efficiency is a never ending one, for better or worse. Mom and pop e-stores were a go-between that except for specific niches are likely casualties of that march.
One of Amazon's biggest problems is that, since they sell everything, and even more everything through third party vendors, they understand very little about most of what they sell. This is why their search is so terrible in many verticals, and probably part of the reason behind the counterfeit goods problem they have. Ship them live weevils in boxes marked "Galaxy S10"-- nobody in recieving will know the difference.
It's a problem with no good solution for them-- even benign stuff like removing obvious duplicates from their catalog would probably cost them precious search results and require huge manual efforts. Going so far as to actually cut off products that sell just because they suck would shake their business model to pieces.
If you go to a "mom-and-pop" shop that's dedicated to one specific niche, they're probably not going to be full of the "noise" products Amazon will have. The specialist enthusiast PC shop won't be stocking weird off-brand SSDs and heatsinks too anemic for modern processors. The camera store doesn't push those $35 Vivitar cameras with a three-megapixel sensor interpolated to 48.
In a way, you're selling confidence-- if I buy any random product in this store, it's much more likely to be an authentic and non-garbage product.
While obviously not a mon-and-pop store, I've definitely heard this argument thrown around about Costco-- they don't have 75 TVs on the store floor, but the 20 they have are probably all reasonable selections in their price range.