I don't possibly see how. The services cost no money, thus they are unequivocally free. Perhaps one could reasonably argue that just because something is free doesn't mean the user isn't entitled to any rights, but torturing the definition of free to suit your argument strikes me as obviously fallacious.
> If they are providing their services for free, how can that be
Because advertisers pay them. This logic is like saying FM radio isn't free because it has ads, this is just not true.
Let say your 'attention', using the service, is used to pay for 'goods', account/ access to service.
How is the revenue derived fron 'attention'? By the attention being spent on preselected content, e.g. ads, that are choosen by the platform. One could argue that revoking access to a service from the platform side is okay since the attention is not being 'spent' after the removal or ban.
It might be feasible to expect that services, like an email account, are not taken away abitrarly but 'just because it's profitable' is not a sound argument. Making yourself dependent on a platform is not the problem of the platform.
If you use Google’s free email, you are not their customer. If you have an AdWords account, you are.
If you don’t like the deal, start charging them money or stop giving your attention to them for what you get in return. It’s that simple.