Guess I can throw my two cents worth in, even though all of my best largemouth came from NC or SC. ( My best smallie came from Erie, 5 pounds, on the Buffalo, NY side).
In many of our waters in the south, it is true that stake beds are added, mainly as cover for newly hatched fry.
That being said, it's not a common thing in NC. Many of our lakes have substantial shoreline vegetation, such as canary grass, primrose, and hydrilla, which offer ample protection, not to mention ambush points for adult bass.
And while it is a fact that Florida strain bass have been stocked in many southern lakes, it's mainly in lakes of the deep south and California, as mentioned above. The record 22 pound four ounce bass came from Georgia, and was almost certainly a Florida strain.
But there are few if any Florida strain bass here in NC, and every year many bass over thirteen pounds are taken in the state, a few over fourteen, and there was a 15 pound fish taken in 2009 from Lake Jordan. I believe it's our longer growing season more than anything else as to why southern largemouth grow bigger.
NC biologists last year shocked up a 16 pound eight ounce fish from my home reservoir here in High Point!
That fish was certainly a northern strain fish.
The Florida strain fish stocked in most of the deep south were stocked to augment, not replace, the naturally occurring bass found there, and there's little doubt they hybridized with the local bass. Florida strain bass also have to be continually stocked, as the northern strain genes will begin to dominate again if the stockings occur north of the Gulf coast states. States with Floridas are California, Texas, Arkansas, Louisiana, Alabama, Tennessee, Arizona, Georgia. There have been sporadic stockings in other southern states, but the stockings didn't take hold.
I firmly believe Ohio has some potential 10 pound plus fish prowling your waters, you just gotta get out there and find 'em!