Why wouldn't it be possible? My friends know what when I show up to a party, I usually bring a drink or a dish or something. There's no centralized database for this, they know because they've eaten and drank those things. We don't use tokens to keep track of this, but we could. The situation seems similar with seeding.
It's just not commonly done because you have to build and maintain a web of trust for it to to work, and that's often a level of user responsibility that's hard to cultivate. But if you need that web of trust anyway (e.g. for filtering out ads ad other disinformation) then you might as well use it for consensus about who is a good citizen and who is not.
(I have no idea if this is Tribler's approach, it's just on my mind because I've been designing something quite like Tribler, and it's my approach.)
It's just not commonly done because you have to build and maintain a web of trust for it to to work, and that's often a level of user responsibility that's hard to cultivate. But if you need that web of trust anyway (e.g. for filtering out ads ad other disinformation) then you might as well use it for consensus about who is a good citizen and who is not.
(I have no idea if this is Tribler's approach, it's just on my mind because I've been designing something quite like Tribler, and it's my approach.)