I edit simply to attempt to increase the readability of topics. Allow me to explain my (good?) intentions in more detail than anyone probably wanted:

(1) I remove full quotations of posts that are directly above the one in question, often because the user has clicked edit: quote reply and not removed the automatically inserted quotation (if I were king, I think I would disable that feature and leave it confined to the multi-quote button actually, no; it is useful but no less of a potential nuisance for that!). In this case, quoting the preceding post in its entirety not only is redundant but also wastes screen space and increases the amount of distance that the reader must scroll in order to navigate through the thread. The user would not have to search backwards in the topic, unless you mean scrolling up a couple of centimetres to read the above post. If the preceding post is quite complex and thus would benefit from a quote, I may attempt to truncate the full-quote to what I think and hope is the relevant portion, as quite rightly suggested by hlloyge.

(2) When a user quotes the whole of a post that is further back, I occasionally try to slim it down if it is large, contains inline images, etc. In this case, the reader can still use the snap-back arrow to locate the original post. But I usually just leave the quote in because, as you said, _m²_, it can be beneficial to the reader, in contrast to full-quoting the above post and thereby somewhat assuming a lack of intelligence and/or extreme laziness on their part.

I can easily believe that I get this wrong, and I apologise to any users who think their quotations have been removed inappropriately; please PM me to explain and have the post reverted if so.

However, I see little justification for quoting the post above your own in its entirety, as I am sure the reader can make the connection in most cases. It does not take much time or energy to consider whether an automatically generated quotation is necessary and to remove it if not, but it does considerably improve readibility when you do.