You're confusing monopolies coopting government to maintain control with large government causing and maintaining monopolies.
Large governments cause monopolies to happen. You said the same thing. Business co-opting a government to creat a monopoly is only possible when the large government exists. You could argue that water and dirt don't cause trees to grow, but without either there is no tree. The language definition is immaterial.
Increases in government size can only occur by taking over parts of the economy into state monopolies. The ultimate large government is a totalitarian communist government, which has a monopoly on everything.
The ultimate cure for monopoly behaviour is a smaller government and more competition by avoiding regulations that favour larger operations over smaller ones.
Microsoft's market position is inseparable from its support by government in the form of software patents. When their rent on Android phones is larger than their income from their own phones, and that rent is purely based on having a patent on an obsolete filesystem which is only useful because it was previously "the standard" (ie., imposed by them), the government is directly helping Microsoft take advantage from their dominant market position in other markets - exactly what they purpose to ban.
(Not a fan of patents, but that wasn't the problem back then).
Meanwhile, the government lawsuit not only did nothing to curb their position (IE kept rising at the same rate), as it gave Microsoft "a special antitrust immunity to license Windows and other 'platform software' under contractual terms that destroy freedom of competition."[1]
That would be the libertarian fantasy, but no, unfortunately that is entirely incorrect.
The "regulations" that you assume make monopolies possible is really unrestricted capitalism in itself, which leads to accumulation of capital in the hands of one or few, often colluding entities.
Capitalism favors larger operations over smaller ones through efficiencies of scale. There is no human-created regulations that do this.
Can you provide one single example of this having happened? I'm willing to believe it, I just haven't found one. Typical examples provided fall short of that claim.
"In 1904, Standard controlled 91 percent of production and 85 percent of final sales." https://en.wikipedia.org/wiki/Standard_Oil
"Due to competition from other firms, their market share had gradually eroded to 70 percent by 1906 which was the year when the antitrust case was filed against Standard, and down to 64 percent by 1911 when Standard was ordered broken up"
And finally, this little tidbit: "The dissolution had actually propelled Rockefeller's personal wealth." Hurray for the Sherman Act..?