IMO all this talk of "antitrust" with regards to big tech is a red herring. At best, it will just facilitate the synergy of government and corporate power, through a "do this or else" cudgel.
What we need is strong privacy legislation (ala GDPR) so that we can actually opt out of being data subjects, and mandated interoperability (through open protocols and published APIs) such that companies have to compete for each user's business rather than just abusing Metcalfe's law.
That legislators don't understand this feels like it's because they don't want to understand this. They see a growing power and their focus is on how they themselves can control that power, rather than how to prevent it for the benefit of all (ie preserve freedom).