That is like saying that Walmart shouldn't take advantage of a form of marketing that was first created by Sears and Roebuck, or Woolworths. But that is what modern historians do, they "cherry pick" their history. Sears and Roebuck and Woolsworth used "sweatshop" labor in New York and Chicago for their products while Walmart uses "sweatshops" in China. Just because we attained a "higher" moral code in this country and banned "sweatshops", does not mean that we don't support sweatshops in China. The merchants in New York got Slavery included in the Constitution for their benefit in 1788, they may have attained a Higher morality in 1827 when they banned the owning of slaves in New York state, but they still wanted the cheap cotton supplied by the Slave states of Virginia, South Carolina and others. So they were just as much involved in promoting slavery as anyone else in 1860.
The discussion of slavery, or property, goes back much farther than the late unpleasentness. It was a southerner who wrote those famous words that "ALL men are created equal". It was that same southerner who sign the 1803 treaty banning the importation of slaves from other countries. Whether that was successful or not is another matters. Those that wants to, will find a way to get around the law. Remember Prohibition?
From the very beginning of this country in 1776 men tried to stopped slavery. It was discussed in the Continental Congress, and the Confederation Congress, and the United States Congress. Even the CONFEDERATE CONSTITUTION banned the emportation of Slaves from all country Except one, The UNITED STATES OF AMERICA. It took a strong President in Thomas Jefferson and a majority in Congress to approve that 1803 treaty. But ending slavery wasn't an easy fight and it wasn't totally southerners who were against that, nor was it totally northerners who were for ending it.
Jefferson Davis in his Inaugural Speech Februaru 18th, 1861 said this,
"An agricultural people, whose chief interest is the export of a commodity required in every manufacturing country, our true policy is peace, and the freest trade which our necessities will permit. It is alike our interest, and that of all those to whom we would sell and from whom we would buy, that there should be the fewest practicable restrictions upon the interchange of commodities. There can be but little rivalry between ours and any manufacturing or navigating community, such as the Northeastern States of the American Union. It must follow, therefore, that a mutual interest would invite good will and kind offices."
That all the Southern people wanted was to be left alone to pursue their own lives and business in peace, BUT:
"If, however, passion or the lust of dominion should cloud the judgment or inflame the ambition of those States, we must prepare to meet the emergency and to maintain, by the final arbitrament of the sword, the position which we have assumed among the nations of the earth."
Bruce Catton in his book "Never Called Retreat" said; "once the war was started, the South would not accept Peace without Independence. And the North would not accept Peace without Union."