I couldn't tell you why the CI is accepted long-term, but the penetrating electrode arrays like the one in the article actually puncture the surface of the brai

I couldn't tell you why the CI is accepted long-term, but the penetrating electrode arrays like the one in the article actually puncture the surface of the brain with tiny needles and cause the surrounding tissue to scar/calcify. There are non-penetrating arrays that sit just above the brain (avoiding this problem to a large degree), but they don't have anywhere near the precision of the penetrating sensors.