I've found the Reject All button _more common_ in the last few months, but due to a lot of sites that have added it also adding a legitimate interests section which is seperate, to the point I'm less trusting of sites that have recently added reject all.

For all the hate that Yahoo gets for theirs (shown above), at least it does have a mostly functional reject all function, even if it requires two button presses (the end of the footer does tell you to go manually opt out of facebook/twitter).