I like it that it can easily be hidden in style; the reason we can hide it in style is that it is a separate element. The OP suggested that it not be a separate element, but be part of the entry element.

Yes, I want dw to not facilitate content which is bad for accessibility, when there are more accessible options.

There is nothing wrong with dw letting us write what we want - I voted for a textbox to let us write what we want. I also don't have a problem with the element being editable on an entry by entry basis, like mood is.

When we crosspost to lj from dw, dw acts as a client. I've also seen entries on dw crossposted from other places with a crosspost footer. The substantive difference is that I choose to read the version crossposted to dreamwidth from wordpress (for example) because it is more convenient for me, and I'm willing to accept an inferior copy for the convenience of having all my feeds and subscriptions on one reading page.

But having an automatic footer text as part of the entry would mean a less accessible original copy for no very compelling reason. I've been to notice board forums, I hate sig lines based on experience not prejudice.