<<It's trivial to edit out the sections that are not needed.>>
That was the obvious solution, but I thought I was somehow not using what was available to simply cut and paste the selected text with a link back.
For what I was doing (a single short section quoted out of a long post) it was easier to cut and paste as originally done, simply because the quote was short and probably would not be tracked back by anyone who had been following the debate, since it was probably quoted more or less as remembered.
The quote button + editing would be useful for the excision of several quotes from various parts of a long post, otherwise it's more trouble than it's worth.