That's a really old mechanic that we've tried to move away from (using items in that way) because it's confusing and isn't really outlined anywhere.

It actually originates from an even older mechanic, where if you had one of those minions on your pet over time it would turn into the final form. Unfortunately without really good documentation that it will happen, users got upset because their minions changed so we added the time machine.

I think that the time machine is a really poor solution to something like this :)