This is actually a beneficial outcome. Similarly to how genetic algorithms and simulated anealing require and element of randomness to avoid getting stuck in local minima, so I suspect advertising serves the purpose of preventing us getting stuck in local minima.
Equally too much randomness and the algorithms fail to converge on the global minimum and so perhaps, too much advertisement prevents us truly discovering the best products and services.
Either way though, it is in finding the balance that real value is found.
I don't disagree that there are many cons, but it's disingenuous not to include the services they power as one of the pluses.
Full disclosure: My career involves ads.
But I can add another minus: ads as a monetization scheme are unnecessarily restrictive, since the only way for an organization to increase their prices is to jump from an ad-based scheme to a paid scheme, and this jump is too big in many cases. Instead, if we paid for everything with money (not with data), then pricing would be more clear and there would not be any threshold in changing prices.
I'd also mention that many freemium businesses actually introduce paid models to control costs rather than improve profitability - particularly true for streaming media companies.
I think this is the most important point. It changes the competitive landscape from being quality-based to being awareness-based.
By driving attention towards their own products, big companies are shifting attention away from more deserving competing products which have a smaller marketing budget.
I think this explains why big companies are so inefficient and yet still maintain their market share.
Advertising allows companies to substitute real quality with perceived quality in order to increase profit margins.
You think small companies would benefit from an advertising ban?
Remember that products can still be found through search. If there are no ads, there will probably be better "product discovery" websites to fill the gap if necessary. And of course there are the regular channels, i.e., recommendations by friends, forums, review sites, etc.
On the plus side:
+ Inform users about products (which is a small convenience).
On the negative side:
- They provide unsollicited information, which distracts and irritates users.
- Users can also search products by themselves (no hand-holding needed).
- They use screen real estate.
- They use bandwidth.
- They use energy.
- They make websites slower.
- They introduce security problems.
- They track users, collect their data.
- They put users in an information bubble.
- Market failure: not the "best" product wins, but the one with the biggest advertisement budget behind it.
- They make people feel inconfident (see photoshopped fashion ads)
So, any value offered by ads is easily canceled by the negative points listed above.