Nobody except Lost Causers "denies" anything factual, but you are placing more importance on such matters than they deserve.
PeaRidge quoting: "Let the South adopt the free-trade system, or that of a tariff for revenue, and these results would likely follow" ~Chicago Daily Times, December 10, 1860
It's most curious that when I go searching for Chicago newspapers in 1860, there is no "Chicago Daily Times", nor was there ever one.
And this would not be the first time that our Lost Causers, desperate to rewrite history to make their side look good, invented necessary quotes out of thin air.
PeaRidge quoting: "...any State which assumes a rebellious attitude will still be obliged to contribute revenue to support the Federal Government or have her commerce entirely destroyed" ~Philadelphia Press, December 21, 1860
Nor can I find any records of a "Philadelphia Press" from 1860, or from any other year.
So I highly suspect the pro-Confederate propaganda machine has been busy, busy, busy at work concocting historical "evidence" to support its Lost Causer mythology.
Regardless, even if we pretend such quotes were true, they would not shift the blame for starting Civil War at Fort Sumter from Jefferson Davis to some amorphous "wealthy Northeasterners".
So it ran for a short period but postdate the Civil War.
Similarly there was a Philadelphia Press, but so far I haven't been able to find a searchable index for any particular story or edition from 1860.