Reality is more complex. Organizing in solidarity is hard, deviation is easy… the whole non-cooperative games theories etc. Markets aren't all zero-sum.

But a bunch of restaurants in a town could all just promote the idea of eating out and promote their directory, and if no premium access or other advertising happens, then it will be best for everyone.

The core point is to reject the simplistic argument that ads are all just information and somehow fine and productive. Maybe you just meant that, in practice, businesses need to advertise. But if we get rid of a whole form of advertising, it can just help businesses rather than harm them. Each additional means to advertise creates yet more burden in a zero-sum race-to-the-bottom fashion.