It's also that dishonesty goes unpunished. Any semi-sentient slime mold can set up a new business with FBA and do the same shitty shopping practices. They'll make enough before they're found out.
It's also why every product is like 4.5 stars -- they just astroturf the reviews by giving away product.
It's not that the internet provides too wide a selection, it's that it fails to provide some very basic pieces of information.
How does the product feel in your hand? Is it soft? Does it feel durable? Does the stitching look neat, or haphazard and frizzy?
When we evaluate a product in person, we make all of these assessments without even thinking about them.