I don't think that's true. If you out two diodes back to back you won't get a functioning transistor. A transistor works by letting current run across because electrons are filling holes in the middle region, this smooths the potential across the entire component, allowing for travel. If you just out diodes back to back, the intervening wire segments disrupt the analogous structure and also the individual diodes probably don't have their potentials calibrated to provide efficient switching action.