"He who has an ear, let him hear what the Spirit says to the churches." ~ Revelation 2:7, 11, 17, 29; 3:6, 13
John was given visionary instruction while he was in the Spirit by the One (introduced in chapter 1 as "like a Son of Man") to write to the angels of seven churches.
Did the Spirit have the same message for all of the churches? Not precisely the same, though some elements are consistent through all.
Did the Spirit want each of the seven churches to know what His message was for the others? One must assume so, or there would have been seven separate epistles.
Would the Spirit today have different message for individual congregations, depending on what their strengths, struggles, challenges and spiritual temperature (hot or cold or lukewarm) might be?
Would He reveal the message(s) to one evangelist acquainted with all of them, to be delivered by him to all of them?
I don't have a specific answer to those last two questions. He might. He might not. But to totally discount His work in this way as impossible, based on no scriptural conclusions, is foolhardy at best. It could be blasphemous at worst.
By that, I mean that it could be seen as men trying to tell God what He can or can't or should or shouldn't or must or must not do through His own Holy Spirit.
And once again, I come back to the doubt that very many church leaders would be open to the possibility of the Spirit operating as He did in the scriptures - through an individual or group of individuals not currently among the membership of their own church.
Is it possible that we don't have the Holy Spirit because we don't ask for Him? Is James 4:1-3 as true about asking for the Holy Spirit as it is about other things we want? Do we want those things more? Do we ask for His wisdom, but while failing to believe God will deliver?
If any of you lacks wisdom, he should ask God, who gives generously to all without finding fault, and it will be given to him. But when he asks, he must believe and not doubt, because he who doubts is like a wave of the sea, blown and tossed by the wind. ~ James 1:5-6
How would the leaders and members of your church react if sent a letter by a former evangelist, or another neighboring church or group of churches, expressing concern over something happening or a teaching shared at your church that might be wrong?
How did Corinth react when Paul wrote them about a man bedding his father's second wife; about their competitive spirit in worship and regarding who baptized them and who was the better teacher; about lawsuits among them? Did they send back a nasty letter that said, "Congregational autonomy! Mind your own blankety-blank business, Paul!"?
I don't think so, or Paul couldn't have said what he did about them after Titus' visit (2 Corinthians 7:8-16).
The problems and challenges of individual churches, if not resolved within themselves by the leaders appointed by the Spirit (Acts 1:12-26; 13:2; 1 Corinthians 12:28), are kingdom business. They witness more than just the shortcomings of individuals or congregations.
They reflect on the Kingdom. They reflect on the King.