[Someone1234]

If there was healthy competition that same number of jobs may be split over multiple companies, but it would still have to exist since the market for the product itself wouldn't change.

That isn't an argument for not breaking up a monopoly. Only an argument that the market may be big enough to support actual competition.

[volkl48]

Look at the beer market. Total beer volume sold is falling. Employment in breweries has doubled since 2010.

Why? Because the market is fragmenting to smaller operations who employ more people per unit of beer produced.

You can argue that from both sides, that it's less efficient vs generates more jobs, of course.