Either because one wishes to make it benefit one's own descendants. In other words, sometimes people inherit at a sufficiently advanced age so that they do not need the property they receive from their own parents. In this case, it is possible to refuse the inheritance so that it passes directly and without additional tax to the next generation. This saves on inheritance fees and taxes to pass on to the next generation later on.
The other reason, and the more common one, is that the deceased person leaves more debts than the assets of the estate. In this case, the law provides for the possibility of refusing the estate. Be careful, the estate can only be refused as of the death and this allows the deceased person not to be required to pay the debts. However, please note that in this case, the persons who ordered the funeral will obviously be obliged to pay it even if the inheritance is refused.