Aaron Peori
Rest in Peace
Maybe it has to do with the age-cap. Exalted can't go above E5 until they hit 101+ years old. Nobody ever bothered to see if humans had a similar limit, because humans don't tend to live much past 100. Even with anagathics available in the First Age the average lifespan is 85 years, with Enlightened mortals reaching about 170 or so. Given that the late First Age when those treatments were common was kind of repressive of anyone not Solar I doubt much experimentation in exceeding the cap occured.
Though, realistically, a thousands of year old Krogan has plenty of time to achieve incredible power just with Essence 3. Dozens if not hundred of martial arts styles, which while inefficient in themselves in aggragate give you access to basically any effect you want, plus all the thaumaturgy you could ever want and Terrestrial Circle Sorcery to cover those things that martial arts can not. Sure, an Enlightened Krogan with two thousand years of XP may not be a match pound for pound to a Solar on the scale of Javik. But he's going to be quite the force to be reckoned with all on his own.
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Epsilon
Though, realistically, a thousands of year old Krogan has plenty of time to achieve incredible power just with Essence 3. Dozens if not hundred of martial arts styles, which while inefficient in themselves in aggragate give you access to basically any effect you want, plus all the thaumaturgy you could ever want and Terrestrial Circle Sorcery to cover those things that martial arts can not. Sure, an Enlightened Krogan with two thousand years of XP may not be a match pound for pound to a Solar on the scale of Javik. But he's going to be quite the force to be reckoned with all on his own.
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Epsilon