Paul was writing his letters to infant churches. Premie churches actually.
He was writing to churches what were not grown up and not one person had a copy of the Bible to read.
Now that we all have a copy, we don't need Paul to guide the church body at all.
Churches are grown up enough to make their own decisions. Mostly because we
have the actual teachings of Jesus, whom Paul never met or ever heard directly speak. We don't even have Pauls written permission to reprint his letters to the individual churches.
That wasn't the primary role for Paul. First, I don't think unavailability of Scripture was an issue. The first Christians were Jews, and they definitely had Scripture available. Gentile Christians probably came from Gentiles who hung around the synagogues. They would have had access as well.
Paul's primary role seems to have been to help the Church decide what Christianity meant for Gentiles. Jesus, after all, had targeted Jews. Paul had to deal with questions like circumcision, the Sabbath, and eating meat sacrificed to idols. Romans is a great book, but it’s not abstract theology. It was written in order to deal with the question of whether you had to become Jewish to be Christian.
The issues he dealt with would not have been solved by better access to Scripture (which for them would be the OT).
When Paul thought about questions, he could be pretty radical. But there’s no reason to think he thought about people who couldn’t have the kind of relationship with the opposite sex that we currently expect in marriage, but wanted to have that kind of relationship with members of their own sex. He mentioned same-gender sex in the course of making a completely different point, and possibly (I still think it’s not clear what the words meant) in a list of sins. It’s not fair to Paul to take those off-hand references to current Jewish standards as eternal law.
Indeed one of he primary differences between conservative and liberal Christians is that liberal Christians think that Christ is not tied down to the particular Jewish culture in which he appeared. Jesus gave the Church the right and responsibility to settle questions like this. (That’s what the power of the keys is.) I believe conservative churches are refusing to do what he charged us with doing.
Paul actually provides an example of the proper use of this authority, in helping Gentile Christians decide what did and what did not apply from the Old Testament. We should follow that example.