I saw that today just before posting this comment which clarifies a lot. You explained the issue better than I did. I realize it's sort of apples to oranges since Venus was exposed to the same elements Earth was at formation and other solar systems might be different because of what they were or were not exposed to. My understanding is that our solar system is in a less crowded area of the Milky Way, on a spiral arm. One would think that stars in more crowded regions were exposed to more. Maybe it's sort of like Earth in that there are deserts, savannahs, rainforests, etc. with different potentials.