In general it seems counterproductive to protect people since that can tend to make the protected people weaker. But advertising is as the parent says nothing but manipulation. It takes away choice from the users, and gives it to advertisers. It's used by businesses such as car dealers to buffer bad practices -- when word of mouth doesn't work, advertise a sale.
A market of free products seems to kill ecosystems like the app store, where so much low quality free stuff is available. But would a 50 cent limit be significantly better? If advertising were eliminated would the world be better or would it just adapt to some other equally ugly configuration. With users paying at least we have that choice & price information that currently isn't there (if the service is otherwise free).