"Targeted" advertising generally refers to the tracking-based targeting of individual people. Re-defining the term to include all types of advertising makes the term mostly useless.
> Doesn't seem feasible.
Banning targeted advertising would be easy with legislation that bans tracking and showing ads to individuals.
> You'd have to make people randomly choose advertising spots from all of media.
Traditional advertising methods worked fine for centuries. Nobody[1] places ads randomly; you advertise where your product's audience will see it.
[1] Advertising intended to build general brand awareness instead of selling a specific product or service might buy ads somewhat randomly, because the goal is simply getting the brand name seen widely and often.