I'm not sure whether direct democracy is really the correct term to use - but I see the point you're making. This idea was touched on by David Stasavage in his article Representation and Consent: Why They Arose in Europe and Not Elsewhere in the Annual Review of Political Science 2016. Stasavage describes the political philosophy that developed in Western Europe was that:
whether one was in an autonomous city republic or a territorial
monarchy, those who governed ought to somehow obtain the consent of
citizens or subjects.
He mentions the Latin phrase 'Quod omnes tangit ab omnibus tractari et approbari debet' (Q. ot ) which is drawn from ancient Roman civil law, and means "What touches all
should be considered and approved by all.". He notes that around the same time that the Duke of Zhou created this idea, so Q. ot was being applied to government in Europe. Most importantly, he notes the distinction between the two philosophies in that:
This statement [regarding the Mandate of Heaven] clearly reflects a theory of government in which those
who rule have obligations to those they govern. The principle of the
Mandate of Heaven had been invoked by emperors of prior dynasties and
would continue to be invoked subsequently. However, the concept of
a Mandate of Heaven never extended to obtaining consent, nor did it
involve assembling representatives to achieve this goal.
I'm not sure whether the term 'democracy', direct or otherwise, can be used to classify a political theory which only obtains implied consent by the virtue of not having been overthrown yet.