This has been mentioned so many times, but it is still prolific, and it includes Heroes and Legendaries who really should know better.
There is no need to quote an opening post in full if you are replying in a thread, and nesting the quotes is even worse. The net result is that a reader will probably skip over your post, and not bother with your reply. This is certainly the case with me. I've even seen senior members just post the quote without adding a comment.
SMF has the option to remove nested quotes. Do you think it would be beneficial if this was implemented here?