> and outlaw advertising entirely?

This is the actual solution, https://news.ycombinator.com/item?id=43595269

The solution is probably not to require them to be paid but to make that a natural consequence.

For example,

1) disallow double-sided marketplace where primary users are monetised to a third party, or

2) require open API and interoperability, allowing users to switch providers easily, mobile phone style.