Re: 'Legitimate purposes'
I've noticed more and more often, reputable UK and EU sites, if you got to their "customise" page, default all but essential cookies as off. Essential cookies, of course, can't be turned off (but can be blocked by you and I). To get there, of course, involves either clicking "Yes/OK" to everything, but at least if you choose the option, they are all off by default. On the down side, Yes is a simple click and the banner goes away while to turn them off is two clicks and an extra page load. But still miles better than some of those disgusting US sites with 120 tracking options, all on by default and must be clicked off one at a time.
(or just block all of them locally)