According to some points of view that is indeed the case. All bar lines and all beats assume the rhythm of up / down. But to me that seems an oversimplification that would seem to imply that all rhythmic vitality comes from either body movement or from speech rhythms. But I maintain that there is often a third source of metric vitality, the play of the mind. Why not imagine a succession of upbeats? or downbeats for that matter?
So you might say it becomes a matter of a prolonged upbeats or downbeat. Okay with me. These are the hardest kinds of meter to produce as the timing is critical as is the touch to keep the listener from automatically doing a toe-tap evasion of this level of humor.
Sticking strictly to the indicated articulations is a great hint as to how this often works. I highly recommend it, especially in music of the Classical period, which is conventionally taught without the slightest heed of the articulations, leaving only beats and bar lines to hang onto.
