With ideal two-way anonymous communications between use-once keys, and completely accountless clearing, unlinkability via blind signatures becomes redundant. This ideal case has yet to be even closely approached with implemented technology, and necessarily involves long communications delays which are often intolerable. Real imperfect communications mixes and less expensive blinded tokens complement each other.
completely accountless clearing
I can't understand what does it mean "acountless clearing" is it just mean "without account", what does it mean "clearing" at the end?