FFS not again...
If I'm not a member of $SiteX and visit $SiteY, I do not want $SiteX setting a cookie. If I wanted $SiteX to set a cookie I'd become a member of $SiteX & then & *ONLY* then have I given permission for $SiteX to know about me... But *ONLY* while ON the site, NOT while roaming elsewhere.
If I get a "Discount Club Card" from the local Tesco, they get to know that I've made a purchase when I arrive at the register & hand the card (cookie) over. They can associate my purchases to my account. That's fine. But they do NOT get to track my every movement beyond their doors. Just because I let them know what I'm buying IN the Tesco store is NOT permission to track what I'm doing anywhere ELSE. Not in the tailor, not the laundromat, not the car wash, not the pub, NOWHERE.
Which is why $SiteX is listed in my Hosts file, cookies from them blocked, and they can Kiss My Fekkin Arse if they get to know ANYTHING about me.
That "Prompt to set a cookie" option of the browser may be a PITA sometimes, but it comes in QUITE handy when $SiteX appears on $SiteY & demands to update itself. What does $SiteX have to do with $SiteY? If it's not jolly well bloody obvious (like I got to $SiteY via an official link from $SiteX), then $SiteX doesn't get to set it's damned cookie.
Just because some wanker of a webdev added a "Like" button to their page is NOT me giving permission to $SiteX to track me there. I don't want your damned cookie, I don't want you tracking me, and you can just go back to your closet beneath the stairs & bugger yourself with a 12u rack of Server Farm.