"Natural monopolies arise where the largest supplier in an industry, often the first supplier in a market, has an overwhelming cost advantage over other actual or potential competitors; this tends to be the case in industries where fixed costs predominate, creating economies of scale that are large in relation to the size of the market, as is the case in water and electricity services. The fixed cost of constructing a competing transmission network is so high, and the marginal cost of transmission for the incumbent so low, that it effectively bars potential competitors from the monopolist's market, acting as an early insurmountable barrier to entry into the market place."
There's a good argument to be made here they all software sub-markets are natural monopolies.
But it seems many aspects of capitalism lend themselves to winner take all mechanics, resulting in large companies (airliners and telecoms and entertainment companies) constantly merging and reducing competition. So without the FTC, we might have even more monopolies. Without these laws, Microsoft would be the only PC company (MS bailed apple out to keep some "competition" around) and Intel would be the only manufacturer of CPUs (likewise for Intel and AMD).