It doesn't allow people to edit who don't have, or don't want to reveal, their e-mail addresses. Requiring registration and an e-mail round trip changes the dynamics of both who can, and who will, get involved.
That's not necessarily a bad thing, but it is a restriction.
True, but that is a choice that I would like to make for the Wikis that I run. Which is the same for the editting "restriction", which was implemented.
Why is this different?
Mischa