If you have a large collection, using tongs to dangle a rodent before each one, which may take many minutes to decide it's hungry, is more than a little bit of inconvenience. It's a tremendous addition of time, which some folks may simply not have to spare. (Time better spent cleaning, etc).

The risk to the snake is really quite minimal, and as I've pointed out, a snake can even be injured by a dead rodent.

I agree that feeding a mouse to a snapping turtle is unnecessary cruelty, I've seen that video as well.
While I've never owned a ferret, it's hard to imagine that a ferret does not kill extremely quickly. I have no opinion on that. I do agree, however, that the ferret would be just as happy with a dead rat, and a toy mouse on a string. Ferrets, after all, are not wild animals.