Rampant Frogantua's second ability counts every player who has lost, no matter how the player lost the game: due to a state-based action (having 0 or less life, trying to draw a card from an empty library, having 10 or more poison counters), because of a spell or effect that states they lose the game, because your awesome might has left them with no choice other than concession, or for any other reason
So like my driving test when I was 16, it passes, but just barely
While you have to be careful to not end up with all spells that protect your creatures and no actual creatures, indestructible is quite potent whether actually printed on the creature or granted some other way
Once I properly understood this card, I immediately thought of Blanka, Ferocious Friendor The Howling Abomination on the Universes Within reprint that is coincidentally in boosters for Phyrexia: All Will Be One