Paul was trying to convince the Jews that Jesus is the Son of God. He said, "remember how God spoke to us through the prophets? Jesus is that God." Before and after Christ, there are those who speak through the Holy Spirit AND have a position of leadership in the church. Before Christ, there were the prophets that you're all familiar with. After Christ, there were the apostles (Peter, Paul, etc.). If you believe that pattern stopped with Christ, then throw away everything from Acts to Revelation (including Hebrews). Paul didn't believe that. In fact, he had a pretty close encounter with Christ Himself.