I'm wondering how many US copyright lawyers are participating in this discussion.
While we're all speaking out of our butts, let me add that simply explicating that by submitting to Wikipedia you're willing to accept authorship credit under the collective name of "Wikipedia contributors" would likely handle any legal considerations.
But IANAL. And it's not like lawyers actually know anything. It's all whistling Dixie until a court rules.
It's less about authorship and more about accountablility. We need those names so we know who to hold responsible if the info is wrong.