But capitalism does what it does best, and will happily take advantage of (and try to prolong) a natural monopoly situation even if the origins were genuine.
In fact this is why there are regulations around "utilities". They are also an area where a natural monopoly is the optimal, so they shouldn't be treated as a free market.
(Food for thought: Perhaps the Internet infrastructure should be a utility too? Browser makers could be forced to be non-profit, which would mean companies need to divest themselves of the "Internet business" if they want to do "business _over_ the Internet")