Only statistically inevitable if those all billions of parallel universes (how many billions are currently hypothesized?) exist to reduce the odds for any one universe to an acceptable number.
Forscher
As you point out, multiple universes is only hypothesized. They are however not really needed in order to reach a sufficient probability, if one does things properly. I should say first of all that I initially don't have much against the thought that some creative, intelligent force could have caused the very first living, replicating organism (I don't oppose the existence of a God). However, it is really not a satisfying answer either, as it will always beg the question of how this immensely complicated being - spirit or not - came to be? If we can afford ourselves the luxury of saying that this creating force "was always there", then we could also allow ourselves the same extravagance when theorizing about evolution of the first cell. In addition, if we postulate a Creator for the first cell, we reach the same point as in all of science to date; if God did it, we can stop asking questions and doing research. God has been attempted to be put into every gap in knowledge of the natural world along the way. However - it is not really necessary. Because - and let me remind everyone that abiogenesis is not a part of the theory of evolution - no one is saying that a living cell of the type we find in nature today spontaneously arrived from prebiotic soup. Following the principle of evolution, it would have had to have come to be in several, very small steps from an "ancestor" replicator:
http://www.talkorigins.org/faqs/abioprob/abioprob.html
As this is only a hypothesis so far, I'm not going to be dogmatic about it, but the odds against it don't have to be as astronomical as creationists often assert.