can someone give me an example of a company that didn't become a monopoly through government intervention
AT&T and the Hudsons Bay Company are both good examples of government intervention breaking up monopolies (Even if they've devolved back into oligopolies)
But in reality what you're asking is "does regulation work to prevent monopolies." The answer is yes. As an example, the FCC has had a rule on single companies not being able to share a TV station along with a radio station or newspaper "in the same market" (for example, in the same city). This is to prevent monopolies (local or otherwise) from forming. And it's worked.
As an example, the Sinclair Media Group already has a massive hold on local TV stations. Up until now, they've been limited from doing a merger by this exact 40-year-standing FCC regulation.
However, now that this regulation has been removed by the FCC, this merger with Tribune Media will allow Sinclair Media Group to reach a monstrous and near-monopoly 72% of american households. Once it goes through, they'll be at near-monopoly status with nothing to stop them anymore.
And media centralization (something that conservatives are very worried about if i remember correctly) is just the most recent example I can think of. Yeah, regulation does prevent monopolies, but even without that, that's not nearly what regulations are limited to. They regulate general anti-competitive practices, help make sure that the free market is upheld (with notable exceptions, corporate lobbying efforts have helped make market entry a near insurmountable cost in many areas), make sure constitutional rights are upheld, and much more.
If your post was to imply that "it's just more red tape," that's really not a valid criticism. Net Neutrality helps uphold fair competition, prevents service provider suppression of free speech on the internet,
stops providers from extorting competitors for money, and upholds pro-consumer values that are important to all citizens.