Well yeah if you put it that way, they don't compete with each other but that doesn't mean they couldn't compete with each other in the future. By being bought out that takes out a potential competitor. I don't know anti-monopoly laws so I'm just throwing around ideas here.
they never would compete with each other. All major cable companies are generally the same thing and won't enter other markets. 1) its VERY expense 2) its VERY slow. Its the same reason why FiOS is dead and Google Fiber takes 5 years to cover .00000000001% of the US
Almost all overbuilders in the US went bankrupt quickly after they completed their build. The infrastructure was bought out and you have pockets where you have two companies, but its rarer then having google fiber in your city