Equality of opportunity, as I understand it (and I think as it was historically broadly understood prior to Marxist socialism becoming mainstream in Mich of the West) meant each person got the same treatment before the law---i.e., no double standard for rich or special treatment for the poor. As soon as one decides what amount of wealth is too much to pass on, one has set an arbitrary limit---is passing $1000 to one's children too much? How is it principally different from $10,000, or from $10 million?
Or, if equal opportunity means equal rights to manage one's property as one sees fit, why set arbitrary restriction on property in monetary or financial form?