2 John has an interesting closing. It says:
I have much to write to you, but I do not want to use paper and ink. Instead, I hope to visit you and talk with you face to face, so that our joy may be complete.
Out of a mere 13 verses (second shortest book in the Bible), he nonetheless chooses to say, "my real teaching is when I visit you and talk with you face to face."
Paul, in 9 of the 13 epistles, starts with some variation of
"I give thanks to God when I think of you."
Two of the others - Galatians and 2 Corinthians - are actually notable for their absence, followed by exceedingly harsh personal rebukes. Thus, personal relationships are front and center in 11 of 13.
Phillipians is explicitly about the link, identifing Paul's personal imprisonment as his primary preaching vehicle:
12 Now I want you to know, brothers and sisters,[b] that what has happened to me has actually served to advance the gospel. 13 As a result, it has become clear throughout the whole palace guard[c] and to everyone else that I am in chains for Christ. 14 And because of my chains, most of the brothers and sisters have become confident in the Lord and dare all the more to proclaim the gospel without fear.
From this, he is able to distinguish between pure-motive preaching and bad - the difference being that bad-motive preaching is for personal ambition. He then continues with the famous "For me to live is Christ, and to die is gain," but then returns to his primary point, saying:
23 I am torn between the two: I desire to depart and be with Christ, which is better by far; 24 but it is more necessary for you that I remain in the body. 25 Convinced of this, I know that I will remain, and I will continue with all of you for your progress and joy in the faith, 26 so that through my being with you again your boasting in Christ Jesus will abound on account of me.
This all show a clear preference for incarnated, face to face communication even over against the permanence of the written word. If generic teaching were to be overemphasized over this pattern, it would be surprising that (especially in light of how expensive letters were!) the writers would all devote space to the focus of interpersonal pleasentries.
But, when read in constant admonition of statements like "be of one accord" and "minister to one another" and "Little Children, Love one Another," that "one-anothering" places this in perfect sense.
The question would then need to be rephrased - What biblical precedent would there be from exempting the preacher from this clear teaching? The answer to that is simple: