[A1kmm]

If allowed, an incumbent monopoly will do the minimum innovation or tactical pricing necessary to keep out competitors - even if it means they suffer a temporary loss.

This can effectively create a barrier to entry high enough that no small company has a chance to beat them. Since insolvency before overcoming the barrier is foreseeable, no one even tries, and the monopoly gets to keep high prices (compared to a competitive market if they weren't there).