I have at least 30 hermits in my biocube and some are over an inch or even bigger AND I have two small clown gobies which are half the size of the hermits and they have all been happy together for years.
If hermits did indeed eat fish and starfish no one would keep them in their tanks. ;lol
I think the situations just presented themselves as the hermits eating healthy fish. believe me when I lose a fish I always always see the clean up crew doing their jobs and "cleaning" up the dead fish. If I lose sight of a fish and suspect its passed all I have to do is look for a mound of hermits and snails to be certain and to locate the missing fish.