The problem with using government to break up companies is regulatory capture (https://en.wikipedia.org/wiki/Regulatory_capture https://en.wikipedia.org/wiki/Re

The problem with using government to break up companies is regulatory capture (https://en.wikipedia.org/wiki/Regulatory_capture https://en.wikipedia.org/wiki/Regulatory_capture). Companies have the interest and resources to influence the very government agencies that are meant to regulate them. They use these influences to steer the regulatory environment to prevent newcomers in the industry.