Before opera shifted to the chrome platform, yes, many years ago, till the version 12, it had an excellent feature : the status bar would list all the URLs from which data was pulled to display a page, along with the file sizes of such data.
for someone who wanted to block content it was a god send. it was easy to see which site pushed the most irrelevant data, and add it to the block url list.
and only opera offered that feature.
it would be great to see a return of that feature. the utility is valued, as much as adblockers. not all sites that push in irrelevant stuff are ad sites. not all ad sites push in the same amount of bloat as well. i dont mind the text ads, but it is the gifs and video ads that i would like to block. and the easiest way to find the biggest pusher is that old feature seen till opera 12.