I would personally phrase it pedantically as not that the natural monopoly is good but that it exists because they are good. A fine distinction and a baked in assumption admittedly that if they were to no longer be good they would no longer dominate. Technically there are some other variables like if an extended stay on top would atrophy any competitors or not and the time scale operated upon.
On a century scale individual murderers aren't a huge concern to society because they are either dead or infirm by then.
On a century scale individual murderers aren't a huge concern to society because they are either dead or infirm by then.