A more generous interpretation is "no ads allowed" means the platform is not funded by advertising, but by public dollars. That way the system design does not become so maliciously driven by engagement/addiction metrics
The roads used to be full of spammers, but governments started banning stuff like prostitution and street peddling to reduce it. And the difference between government and a social media platform is that the government will go to your home and fine you dollars or put you behind bars if you run a professional spamming agency. So I think a government run option would have way less spam in the long run, but almost surely less freedom as well which might not be what people want either. We already see people getting arrested for relatively minor comments they post on social media in UK.
To be clear, in my vision of this, people would be allowed to advertise however they want. Businesses could have accounts. But having a space for ads and then using behavioral ad targeting would be out.
In your vision of it, perhaps. Citizen's United, however, has already decreed that corporations have free speech rights like everybody else. By creating a distinction between commercial and personal speech, the government would be interfering in the 1st amendement rights of personal and commercial entities.
My vision doesn’t create a distinction between commercial and personal speech. In fact, it does the opposite, by not privileging commercial speech and giving it a special space on the page. If you want to advertise you wares, do so, but you don’t get to pay to get attention. Get people to follow you because they like what you have to say.
When you wrote "having a space for ads and then using behavioral ad targeting would be out", I understood it to mean that you did not want any space at all for ads and not just a lack of designated space for ads.
With that being said, the only way I see this happening is if the government builds its own ISP and /or IXP, secures its own peering agreements (with the understanding that another ISP can refuse), hosts the website on its own servers, and accepts all potential spam that comes from all of its users.
In addition, none of this will stop tracking by ads using tricks like the Facebook Pixel, obfuscated analytics, or fingerprinting scripts as code is also free speech. In fact, none of stops any tracking on server-side by government agents either. Any IP logs or information that's gleaned from user access of government services is understood to be self-incriminating and will be treated as such as in the case of a drug dealer in Massachusetts.[1]
All in all, who is expected to pay for all this (and on what grounds) and how do you intend to stop ads or any tracking at all with these factors involved?
Oh the users would most certainly be tracked by the government. In fact, that's part of the point. One of the unfortunate byproducts of Parler getting shut down was the loss of visibility of right-wing terrorists.