You must be reading different things than I am. One can find article after article on the tariff, if one is looking for it. Check out what southerners were saying to Englishmen in particular, since slavery wasn't so palatable over there. They tried to spin their concern over the tariff into the
main cause when they wrote for Englishmen--unsuccessfully in many cases, but still:
"The author of
The American Crisis quotes the [London]
Times as his authority for saying that it is not slavery, but protection, which has caused the disruption of the republic. This is, no doubt, what Southern politicians invariably put forward as the plea to enlist European sympathy. And no doubt, also, that the indecent haste with which the Morrill tariff was enacted during the very thores of separation has contributed more than anything else to support such a plea. But let us look at facts..."
Source.
Englishman Samuel Pope, speaking at a meeting in Manchester, England:
"It was slavery, and nothing but slavery. [Pope] knew it was said in this country that it was not slavery which was the cause of the war; that it was long-standing grievances, and especially grievances with regard to tariffs. He knew that was said in this country, but it was a little singular that it was not said anywhere else... because this particular question of tariff was one which caught the imagination of the English people."
Source
So southerners were over-exaggerating the importance of the tariff to please their English audiences, but there was still a kernel of truth to it--the fear of a higher tariff, with its profits and protection going to the north,
had been a thorn in their side. We only need to deny this because we live in the 21st century and the position has been forced on us, just like it was forced on England, so we need to over-exaggerate the opposite view.
But the war's over. It's time to stop worrying about spinning arguments to be palatable to the anti-slavery demographic, and it's time to stop letting those arguments frame the discussion.
Exactly. But they're forcing a false dichotomy. Where are period southerners saying the tariff
wasn't important? Slavery was the main crisis they were focussed on, but only because we live in the 21st century do we have to argue that the tariff was
unimportant, in order to argue that slavery
was.