In Luke 2 the shepherds prophesied over Jesus. All marveled, but Mary treasured these things and pondered them in her heart. Many can enjoy and feel edified by prophetic words, but it can sometimes take years for a word to come about. Mary's heart was the womb of of the word of God. She gave that word a safe place to be preserved and protected.
Hebrews says that by faith they inherited promises. Faith attracts promises into people's lives. The Lord has a destiny for humanity of divine encounter that even the biggest dreamer could not imagine. The Lord wants to find people He can rest on so that they can bring forth a word of God.