> 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.

There shouldn't be "mass layoffs" for that reason. If they are both reasonably large companies, the size of the HR department depends on the number of employees. When you merge the companies, the number of employees initially stays the same, hence there is no HR to be fired. You might consolidate the HR departments, and this might lead to some roles becoming redundant, but not on a mass scale. Similarly for accounting, marketing, etc.

The fact is that there are no synergies for many companies, even companies operating in the same industry. The reason for promoting a merger between such companies is exactly that they will see reduced competition and hence greater profitability. The ideal merger is actually between companies making different products, where the one company can benefit from more vertical integration.

This is wrong

Which part exactly? Seems you just described why the layoffs happen? Two things can be true here, the new company can find cost savings by eliminating redundancies and have to cut deeper than desired to be able to service debt.

The higher prices is also wrong, adjusted for inflation. And the lower-quality products is subjective at best.

I really hate when authors undermine their own (often valid) points.