I think you're wrong. Those companies are already unassailable monopolies. For all intents and purposes, they've become public utilities, which, because of their outsized dominance over internet content, communications, and commerce, must be forced to adhere to the same sorts of rules and regulations other behemoth companies must follow.
We currently have only one method of bringing such megalithic organizations to heel, and that's through the power of government. Let us not forget that the federal government ostensibly exists solely to serve the people. This is one of the few areas where it still does.
The big tech companies have brought this heat upon themselves. They chose to put the liberal ideology of their principal members ahead of profits, which in turn created a corporate cultural climate of hate and discrimination against conservative individuals and groups.
That unmitigated anti-social behavior has resulted in real and active suppression of conservative speech and activism across those platforms. As you well know, scores of prominent conservatives have had their accounts suspended, terminated, demonetized, throttled, de-linked, shadow banned, and/or censored. Some, like Alex Jones, have been completely de-platformed, I.e., run off the internet entirely. That takes collusion across corporate walls.
If the same egregious treatment were being dished out to prominent mainstream liberals, we could perhaps make the case that these companies are simply adhering to their internal policies in an even handed manner, but they're not.
Obviously I'm not in favor of big government solutions to everything that ails us, but there are situations that our government is properly suited handle. This is one of them.
I don't subscribe to utopianism.
And no, they aren't monopolies. Only if you accept the progressives' definition of the word "monopoly".