Using a Kona, Rescue Beastie deck (or any survivor mechanics for that matter), Saruli Caretaker should be an excellent way of easily tapping your creatures to get their Survivor mechanic to trigger. However, if you don't have any spells in hand to cast or abilities to activate the game will skip past your main phase and combat before you ever have a chance to tap your Survivor with Saruli Caretaker (or any other permanent with a similar effeect). Since Saruli Caretaker's ability directly interacts with another permanent it should be treated differently than other mana dorks.