Well, I won’t contest your points. As I said, it may have been ultimately unavoidable. We had a brief window of opportunity between 1776-1789 and it was lost. Another problem with the Confederacy is that a pure states rights republic simply wasn’t going to be workable. Even in conducting war policy, that was apparent, you’re going to have to have some level of centralization or you’re going to have to have each state as an independent republic (and I could imagine there being another Civil War within the CSA before long).
You cited the “gay lobby”, an example of that is the current push for marriage. You can’t have it so that your marriage is valid in one state (albeit by however contorted means they arrived at it being remotely legal or permissable under a given state Constitution) and yet not in another, so all they merely need do is get it “approved” in a few states, go to another demanding their marriage of another state be recognized and have it set up to go to SCOTUS to have it imposed on the rest of the country (a la Roe v. Wade).
The Constitutional Convention/Continental Congress was probably the only time to deal with slavery, so it was a catch 22: either you had a nation with slavery, or you didn't have a nation---but you'd still have mini-nations with slavery.