Even if that features worked, it would still be user hostile to force them solve a global problem locally.

If Google really cared about user experience, they would already have downscored all those low-quality sites years ago. But they don't - neither now nor back then. So either they are profiting from those low-quality sites, or they simply don't care.

The more I think the more intentional this feels. I mean, if Google really wanted to filter out low quality websites out form their search results, I can't imagine much more reliable algorithm than to ask from the users to indicate the results that are bad.