The main issue you're describing I think is just how profitable it is to own the platform. In the same way that ads are an unstoppable firehouse of money, so are toll booth charges on your platform.
One thing that's frustrating and perhaps part of why it gets posted about so often is that it does not have to be that way and the underlying internet itself is not that way. So if you grew up on the early internet you have some (perhaps rose colored) memories of a better way. Or even looking at models like Wikipedia, (or for some people crypto but I tend to be suspicious of toll booths cropping up in that ecosystem too.)
Problems like this can theoretically be regulated away? It's hard for me to imagine.
Unsophisticated regulators working on nuanced problems often write policy that unintentially stengthens incumbents. Maybe if you had some really good regulation you could do it that way.
The other option, I think the better option. Is for people (some of which I'm sure are on this very website) to build software that does what it says on the tin really well rather than exploiting people (like Wikipedia).
The other thing you have to do is come up with a survivable revenue model. Here, you unfortunately have to be an idealist. Wikipedia for example takes in massive amounts of money in donations every year. However, that is a tiny amount of money compared to what they would make....if turned on ads on Wikipedia for one day (thanks for not doing that Jimmy!)
Another way would be to not settle for idealism and find a better revenue model than advertising and toll roads. This could really be it's own undertaking to solve the problem. Don't estimate how hard that is though or just how profitable those models are.