[Djvacto]

But the companies use of telemarketers isn't a net benefit to society. If the company instead spent on product quality, warranty services, employee benefits, or charity, we'd see more of a net-positive impact on the world around us. Generally, companies spending money competing for market share through advertising only benefits specific parties, and only financially.

The goals and incentives (for companies) aren't currently aligned with our needs & problems (as a society). So a lot of resources get spent on things like advertising, that (in theory) could instead be spent on solving problems related to housing, healthcare, infrastructure, if the incentives existed or the goals were set differently.

[Detrytus]

Who decides what is a net benefit to society?

In capitalism people vote with their own money: if there is a demand for some good or service it keeps getting provided.

Of course you might argue, that average person can be manipulated into buying things that are harmful to them, but if you want to prevent that there's really no way to do that efficiently other than turning the whole country into a totalitarian surveillance state. And you also need an elite, a group of people who are above the law because they are just smarter, and know better and therefore set the rules for lesser beings.