> In reality, mergers like this — particularly when involving Warner Brothers — have a long history of resulting in mass layoffs, higher prices, and lower-quality product as the merged company tries to pay down debt from the deal.

This is wrong. There are mass layoffs because you don't need 2 HR departments, 2 Accounting departments, and so on. You can often do away with lots of sales & marketing too, in some industries.

These are called "cost synergies" in M&A, and are basically the only synergies someone will give you credit for in a deal.

Debt financing is not required for there to be cost synergies.