That article gives more examples of ways monopolies occur without government intervention, such as mergers and takeovers, and collusion and price fixing. All of these things have happened multiple times in the past, so history provides all the proof we need that lobbying or other government assistance is not required for monopolies to form.
Unfortunately competition still doesn’t always work, because crafty companies know how to fix prices without explicitly colluding - witness the insulin market, for example. I don’t particularly believe that my cell phone plan prices are the result of providers competing on price, it often seems more like a silent unspoken agreement among the providers to not lower the prices, which in addition to insulin has happened in lots of other markets.