People have pursued such donation based models.
Nobody has succeeded in making substantial money on a per item basis. However NPR manages to do it on a brand-based basis, but their signup rates are something like under 1% of their dedicated listeners. It isn't easy.
If you could attach a frictionless transaction to a "Like" or "Kudos", I would be happy to pay $1 a pop or something reasonable for a well researched blog post after I've read it. Maybe not feasible for a wider public, but certainly might have niche acceptance.