Note that eliminating the ability to do detailed profiling and precise targeting does NOT stop this kind of manipulation. It just makes it more expensive.

Those people who will respond to your fake news in a way favorable to you are still out there. It just means that instead of being able to target a group of say, 10 000 people that will give you a 5% conversion rate, you might have to pay to target 1 000 000 people with a 0.05% conversion rate.

This raises an interesting question: would we be better off if instead of restricting data we make it more widely available?

As suggested in the second paragraph above, restricting the data doesn't stop those with enough money from influencing susceptible people at scale. It just makes it more expensive, so only the very wealthy can do it.

If we make the data more open, we make the playing field more level, perhaps giving smaller, less well financed groups a chance to compete with the billionaire backed groups and causes.