...Nope, it would have been valid had the South won the War for Independence. We lost because of General Lee's strategy.
You lost for several reasons...
1. you lacked a sufficient internal manufacturing capacity and related resources
2. you were a primarily agrarian economy, unsuited for warfare against a more populous and urbanized and better-organized adversary
3. you made the mistake of not freeing your slaves
before you began to fight; thereby smearing your cause with the feces of slavery
You had arguably the best general on the face of the planet back them (Robert E. Lee).
Nobody else could have held the South's military together and kept it effective and held the love and loyalty of his men right up to the end.
It took us a dozen generals and a great many phukk-ups before we managed to beat him down.
Given your extreme disadvantages (see 1-3, above), you would not have lasted anywhere
NEAR as long as you did, without Robert E. Lee.
You did not
lose because of Lee's strategy...
you lasted as long as you did, because of Lee's strategy.
You were doomed to lose from the outset... it's a bloody miracle you lasted as long as you did... and Bobbie Lee... a great American general... gets credit for that.