Why should they if they’re buying some commoditized item on amazon, for example? I bought an ergonomic ice pack for my knee this morning, something I couldn’t find in the store near my house. Why should I scroll past the first, cheapest, decent looking item that meets my needs? As a moral duty, perhaps. At any rate, advertisement doesn’t necessarily mean scam.

When you pay for an advertised product you're also paying for their advertising budget hence most likely not the best price/quality. Sure, not 100% true all the time, sometimes there's a liquidation of stock or something like that.