As stated in the review, and presumably in the book: that "the very bigness of present-day companies — especially those in the tech sector — does not just harm consumers, but that it also threatens innovation and undermines the power of government."
The problem that trust-busting is meant to solve is the bigness, and its impact on the government, innovation, and consumer markets.
It's up to the book to make that case. My point is that the issues you describe (misinformation, polarization, engagement baiting, objectionable content) are not mentioned among the problems that trust-busting is meant to solve. Other problems are mentioned.
