This is completely counter intuitive. The ancients used rhetoric, frequently.

Paul is saying that he is throwing all his training and technique away.

1 Corinthians 2:

1When I came to you, brothers and sisters I did not come proclaiming the mystery of God to you in lofty words or wisdom. 2,For I decided to know nothing among you except Jesus Christ, and him crucified. 3And I came to you in weakness and in fear and in much trembling. 4My speech and my proclamation were not with plausible words of wisdom, but with a demonstration of the Spirit and of power, 5so that your faith might rest not on human wisdom but on the power of God.

via Daily Lectionary Readings — Devotions and Readings — Mission and Ministry — GAMC.

I quote Alte a lot. In part it is because this woman has both a germanic mother (for rigor) and a classical catholic training. She teaches rhetoric, and does it well.

This is from her outline essay on this topic.

We use this classical structure, divided into parts, to guide our audience through our speech, to make our speech as persuasive as possible, and to ensure the completeness of our argument. Whether an argument is correct (logical and true), rather than complete or persuasive, is not within the scope of rhetoric.

The parts are: exordium, narratio, partitio, confirmatio, refutatio, peroratio. In modern writing instruction, these are often condensed into introduction (exordium and narratio), body (partitio, confirmatio, refutatio), and conclusion (peroratio). The introduction and conclusion generally appear only once, while the body may appear once or be repeated for subtopics. The classical rhetorical writers and orators (such as Cicero and Quintilian) have disagreed on the precise number, and the order of the subparts is not always consistent, but that is a good general list of the various parts.

Paul was both a Roman Citizen and a trained Rabbi. His education would have included studying rhetoric — it was a standard topic — as well as how to argue the Torah using rabbinical techniques. He was the most theologically equipped of the apostles: he had studied with the best (Gamaliel) , at the best place place (Jerusalem). And he threw it away.

It seems that he did not want technique to sway people but the spirit. Today is Pentecost. We need to look behind the polish of our ceremonies and the tricks of speech that move us emotionally and discern what is truth, and what  is the work of the Holy Spirit.