There are tons of reasons. New location just opened. New product is available. Improvement to old product was released. Inventory clearance sale is about to happen. Seasonal businesses that are just entering the season. New consumers who might not be familiar with the products available to them.

I work in a business that serves a lot of local advertisers. We do take national and agency client business, but the majority of our work is with local businesses. They do it because it works. People hear the ad and foot and digital traffic to their locations increases.

Advertising is just a market. "Advertisers" are just people with a business who want to reach consumers. I'd be far more comfortable with the case that, as a market, it should be policed by some administrative agency, and like most administrative agencies over the past few decades they're likely asleep at the switch and so the market shows obvious signs of abuse.

This is why I, and the other poster, take some umbrage to what seems to be a very simplistic elitist take from you. This is a market. It has benefits, and it has the potential for abuse. Rather than looking at this as a social problem that simply needs basic agency actions to be solved to defend those benefits, the rather radical idealism of destroying the market entirely gets bandied about a little too comfortably.