The 13th Amendment was ratified and became law by 6 December 1865. In 1859 or 1860 slavery was firmly established in a large part of the United States, by 1866 it was gone. That was quite an achievement. I certainly wish it could have been accomplished without war, but it won't do to minimize or demean what was done.
Lincoln couldn't free all the slaves by executive proclamation. That would have been unconstitutional, and would have been regarded as tyrannical, so the Emancipation Proclamation only applied to areas in rebellion against the US. It derived its legitimacy from the President's war powers, and those wouldn't have applied to areas not actively in rebellion.
But three years later, the remaining slaves in America were freed by a constitutional amendment. It was the only way it could have been done. Lincoln had pushed for it, and the Republicans urged ratification of the amendment as a tribute to him after his assassination. Well before 1865, slaveowners could see the "handwriting on the wall" and chose a side to fight on accordingly, effectively choosing slavery and rebellion or emancipation and union.
If they'd had their way, the Confederates might have waited generations before freeing all the slaves on their territory, and you complain that three years elapsed between the Emancipation Proclamation and the final emancipation of the last slaves. That looks cockeyed.
Frederick Douglass, no fan of Lincoln's, summed up: "Viewed from the genuine abolition ground, Mr. Lincoln seemed tardy, cold, dull, and indifferent; but measuring him by the sentiment of his country, a sentiment he was bound as a statesman to consult, he was swift, zealous, radical, and determined."
So many of the "arguments" made by defenders of the Confederacy are false or weak. People blame Lincoln for not having felt a certain way or done a certain thing at a given point in time, ignoring the real progress that he made in his lifetime, and give Confederates or Southerners an eternity to get "right" on questions like slavery, segregation or racial equality. Or they blame Northerners for having slaves in 1770 or 1820, and absolve Southerners who had slaves in 1860 and weren't going to get rid of them.
So much of the talk of "Northern hypocrisy" just amounts to Southern hypocrisy. We've had faults and weaknesses as a nation, but there's no justification for the kind of slight of hand that some people practice to make Southern slaveowners come off looking better than they should and better than their opponents.
You want to talk hypocricy? Then tell me why the 13th Amendment was accepted yet when the 14th Amendment was constitutionally rejected, that the northern states refused to seat the 1869 southern representatives, suddenly declaring them illegitimate? If they were illegitimate, then the 13th Amendment was illegitimate, too, was it not?