There's plenty of evidence Mars once had much more surface water than it does today. IIRC liquid water is one of the primary preconditions for the evolution of Earth-like life.
What about Mars disfavoured it?
In two hundred years, conclusions drawn from what we currently know will be as out of date as conclusions from two hundred years ago are today. Or to put it another way, things known to the best of our knowledge are both as good as we can do and probably wrong because one of the things we know is that historically most of what people know at any given time turns out to be wrong at any given time.
I'm entirely down for our descendants in 200 years laughing at our scientific parochiality, just like we often get to do at our double-century antecedents. But that doesn't justify writing right now that Mars and Earth have a priori likelihoods of being the origin of life in the solar system.
I think the author was trying to say "I mean, look, Earth and Mars are not that different, and even though we don't have any current evidence for the appropriate chemical conditions on Mars, I don't see why it couldn't have been where life started instead of Earth, because ... well, just because they're sort of similar, kind of. Oh, and next to each other."