The only safeguard would be sensible policy.

Problem is that politicians ask "big tech". Few of these companies have an interest of collecting less information. On the contrary, they would probably try to sell access to their data in the process.

I don't think advertisers would care too much about not being allowed to collect certain info as long as they can be sure their competitors are subjected to the same rules.

…after spending a substantial amount of R&D into how to brainwash you into artificially inflating your value estimation.

The deception is fractal, with makes it just so much harder to overcome.

As soon as a customer has made a choice between two suppliers, then any marketing for the other one will be considered invasive. By definition it isn't wanted because the customer chose not to use that supplier. Consequently any marketing will always be seen as invasive by some people, unless the market is a monopoly, and therefore all marketing is problematic (or "evil").