It might be free as in gratis (free beer), but it's not free at all. Your behaviour, your profile, your data: you are the one giving that away in exchange. That data of yours is valuable.

And IMHO even more importantly, with advertising the dynamic between content provider and user completely changes. The user no longer primarily is a customer, but rather becomes the product for the advertisers. The content provider no longer only has to cater to the user, but also to the advertiser, with the conflicts of interest that can bring (e.g. unpopularity of critical product reviews).

Restricting the legality of advertisements in general might have the nice effect of leveling the playing field, by making it harder for content providers to benefit by-generally covertly-selling out their users (or their users' interests) to such third parties.

It isn't free as in speech without ads either. You give up your behavior, profile, data no matter the site showing ads or not. What you wrote sounds like a pro-ad argument when thought about for a second.

I agree with your first two sentences, not the last one though. I didn't even mention ads in my comment :)

You give them some of your brain time which they're reselling to the highest bidder.

You either use that brain time to generate income at work and then hand over that money, or use it in real-time to pay for the content. Ads are much faster and easier in that regard.

Which is not money, thus its free.