There's nothing that prevents people from wiping or editing non-root posts. And even a non-root post could root a sub-tree of tens of postings. I don't see that the possible wiping or
editing or a rooted post is that much worse that one should
be banned, while the other doesn't have much of a barrier at
all.
I'd also have the feeling that mosts posts that will be edited
are edited relatively short after it was posted. So, if the
problem is that one doesn't want front-paged notes to be edited, a solution (instead of banning the editing all together), is to not front page nodes in the first N hours
after they get posted. This has the added benefit that one
could look at the first responses to see whether the original question is worth front paging it.
Abigail