Because I don't think those conditions were necessary for life. I think life formed as it did because of the environment (there's no advantage to tolerating free oxygen if it's not around). I don't see anything inherently difficult about surviving in an oxygen- (or methane-, or nitrogen-) rich environment, unlike (say) in a high x-ray emission environment.
But I could be convinced otherwise. Why do you think that abiogenesis requires conditions like the early Earth?
Miller-Urey and Miller-Urey-like experiments (which managed to produce nucleic and amino acids) have always been performed in a reducing atmosphere. Sure, that was to try to replicate the early conditions on our earth, and with an end goal of producing the biochemistry we have today, but are there any oxidizing equivalents?