To be fair, I think there is some argument that some of the larger tech giants would benefit consumer welfare by being broken up. Facebook probably less so since people already have choice.
Warren does herself no favors by using $25 billion as the threshold of a monopoly. What a real monopoly is is when there is no consumer choice at all, leading to large corporate profits that hurt consumers at the pricing level.
By not using consumer choice or harm as the standard (which is what the court uses), Warren comes across (and perhaps actually intends) to be against large companies, regardless of welfare.
