According to Mongo documentation in order to safely deploy a replication set, you need at least two active and one arbiter because election of the a primary needs the majorities of the votes.
Let's say I'm able to have three machines, therefore deploy three full-blown mongo instances, no arbiter.
If the elected primary fails I end up with TWO nodes, where both of them has the same "power" level: for me this seems to be the must-aviod situation described at the deploy.
Can someone unfold why is it not a problem to elect a primary in this situation when it is if the initial setup is the same?