Not true. Stuart left something like two brigades of cavalry with Lee, concededly under subordinates he didn’t like. But they did a capable job of screening Lee’s right flank on the march north and reconning ahead. what Lee didn’t have was Stuart. But Lee’s orders [read suggestions] left Stuart the latitude to try tanother risde around the Union Army. This time it didn’t work. But Lee had cavalry. He just didn’t use it well.
And as for the North’s luck, to paraphrase Georger Pickett explaining the South’s loss, the Army of the Potomac had something to do with that.
To some folks every Confederate general OTHER than Lee was responsible for their defeat at Gettysburg.