I do not know of any research about early walking etc but I do think that using a baby bouncer has very little to do with a natural way to stimulate abilities. You have to consider that a human being is not fully developed until 16-17 years of age (the brain is still developing til the age of 7-8). The physical development of a child is, at least in literature, closely related to to its mental/psychological development as so one can observe differences in development of children. One develop faster physically another mentally.
But understand well that a child doesn't need any help in the form of a baby bouncer to develop. In opposite one has to consider if the bones which are at that age not very bony but more or less cartilage like. But nowadays there is a tendency to let children read at an age which they should use for other things. Who cares?