Those are very good points - I was thinking about this when I wrote of multiple pressures. A lot of these platforms have pulled a bait and switch in regards to their rules, not being upfront and consistent at all.

How much of an option "voting with your feet" amounts to, depends on two variables (that come to mind): the variety of alternative options available (from websites to browsers, v.p.n.'s, and even different s.p.'s), and how much of the aggregate population can become well informed on these matters. More specifically, how well informed are the people that one needs to communicate with in these ways.

From what I can see the options for migrating contacts is mostly between large platforms. I know that minds.com has a migration option from facebook, at least in general.

I'm also aware of how "voting with your feet" can mean giving up ground upon which you've invested, to say nothing of the many costs of moving (including the strategic implications of giving up ground). The strongest argument to make in respect to this is to confront the arbitrary practice of rules set by the owners of those platforms, and that they need to be held responsible to their word.

Your earlier point about transparency from the top down relative to power corresponds with a lot of this. A Discord group, for example, setting it's own rules, can bring more of a "take it or leave it" approach. But even at that level it's important not to bait and switch people on your rules. And the way that power tends to consolidate into control over others, is always a thing to keep in mind.

Having different transparency relative to power can only be effective when people are well informed going in to a platform, otherwise you end up relying on an even more powerful entity imposing transparency rules on that platform. And that larger entity comes with it's own propensity for corruption and arbitrary rule. Unfortunately most of us have been duped into a lot of these platforms, and it will take a great deal of difficult work to find a workable solution.

Will blockchain technology render the freedom to choose obsolete? Or could it enhance such freedom? I think that freedom and responsibility, for what you choose to bring to others, go hand in hand. They are not opposites.

A quick possible example of strategically effective "voting with your feet": the history of Image Comics.