We should not AIways Involve Everybody
I have experienced bottom-up approach in numerous cases and with good results in most cases. It is clear that this approach is not advised for all decisions. It is very important to distinguish the appropriate cases. For example it can not be done for cases in which the bottom levels have no information about the issue at hand.
And also it does not mean that all employee have to participate in all decisions. In some cases only the employees of relevant departments should be engaged.