Occam's razor is only useful if it removes complexity. Since amino acids can form just as easily on comets, for instance, how is it any more plausible to form on earth? All our water comes from comets; it would be ludicrous to think it's not also a source of organic material. Indeed, Philae confirmed that organic molecules were abundant on the comet on which it landed.
Now whether RNA came from a comet is another story, and one that will probably be very difficult to answer, given the lack of archeological evidence.
And finally, what does it matter where our RNA came from? Our roots are in these tiny, self-assembling structures. That's the miracle. It's not like we're surrounded by other solar systems that may be candidates for precursors to our life: either life sat around in a very primitive form for probably billions of years before coming to rest at earth, or it formed somewhere in the vicinity of our solar system.
Now whether RNA came from a comet is another story, and one that will probably be very difficult to answer, given the lack of archeological evidence.
And finally, what does it matter where our RNA came from? Our roots are in these tiny, self-assembling structures. That's the miracle. It's not like we're surrounded by other solar systems that may be candidates for precursors to our life: either life sat around in a very primitive form for probably billions of years before coming to rest at earth, or it formed somewhere in the vicinity of our solar system.