[…] when I got there it had started and there were no seats left. Secretly relieved, I walked or rather mountaineered back to the flat […]

The others, whose time had been more actively employed, began to shew symptoms of innovation,—the good wine did its good office. The frost of etiquette, and pride of birth, began to give way before the genial blessings of this benign constellation, and the formal appellatives with which the three dignitaries had hitherto addressed each other, were now familiarly abbreviated into Tully, Bally, and Killie. ― Sir Walter Scott, Waverley, ch. xi.

The prevailing wisdom today is that any benefits of vertical integration tend to be outweighed by the greater advantages of specializing in a narrow range of vertical activities.

This point is explained below.