Online advertising is great for brands. It's bad for: indie stores.
Why? Before the Internet, there were few ways for brands to cut out stores. They may have an annual warehouse sale, but that was about it. Today, a customer visits a retailer website and looks at brand X. Or it visits brand X's site to do some research. The issue for indie stores: thanks to online advertising, now I'm being marketed to across the web. I'm reading news on the New York Post website and being encouraged to buy directly from the brand. This is not good for the indie store.
Notably, brands or their sales reps may ask a store why the store is not selling more? Meanwhile, every year the brand's direct-to-consumer (D2C) sales are increasing. Does the brand not realize the sales it's gaining are coming out of the pocket of indie stores? It's cruel to ask a store why its sales are down for brand X while that very brand X is running direct-to-consumer ad campaigns to the store's customers.
You may ask: why is online advertising bad for indie stores if they can also use it? Because they are put in a bidding war against their brands to run those ads. Brands, since they have 2x the margin, can afford to spend more on the ad campaigns. They drive up the advertising costs, edging out the retailers.
The biggest winners in online advertising are brands and ad networks (Google, Facebook, etc.).
Please note: For privacy considerations, I've covered the brand's logo with a yellow box.