Agree. Slavery would have eventually faded on its own in the American south much as it faded in the north and in much of the British Empire. It was not an economically viable model with the advent of industrialized agriculture. There was no need to agitate for war to end an institution that would probably have disappeared within a few decades on its own. Only a fanatic would think that the institution of slavery is worse than a bloody war among countrymen.
Andrew Jackson told Sam Houston, his youngest protege, that, if he lived to see proposals to divide the Union over the question of slavery, Houston must run for POTUS (he was then president of the Republic of Texas but Jackson assumed that Texas would join the Union) and, if victorious, declare war on all of Europe before allowing a civil war. Then slavery could be allowed to die a natural economic death and leave far less in the way of a permanent rupture of the American experiment.
Sam Houston was no admirer of Lincoln, but he opposed the secession of Texas to his last days.
Slavery flourished for a long time throughout the Americas but the worst heritage was left by British, race-based, slavery which made no provision for the ultimate freedom of the slaves or their progeny or their integration into society. This is the heritage of American slavery left us by the Brits. The slavery practiced in Spanish and Portuguese possessions encouraged intermarriage and always conceded the humanity of the slaves and the importance of their salvation. Few Mexicans, for example, are pure blooded Indians. Fewer still are pure blooded Spaniards.
In most of Latin America, the social hierarchy is very much based on race, probably more so than in the US: the ruling elites of Mexico and most other Latin American countries have more European blood while the underclass is largely Amerindindian (or of mixed African/Indian ancestry in the case of Brazil). The difference is that unlike the US, Latin American countries don't have a binary classification with a "one drop rule" - it's not a question of whether you're Blanco or Indio, it's a question of how much more Blanco you are than the Indio who mows your lawn.
Whatever Thomas Jefferson may or may not have been doing with Sally Hemmings who was his late wife's half sister but also half black having had a slave mother, marriage was not encouraged between the two because the racial difference would have been a scandal in Virginia which had Brit roots.
Indeed, as to Sam Houston, he left public life rather than accept secession after he tried unsuccessfully for the Democrat nomination for POTUS in 1860.