It would be kinda hard for an individual web site to develop a meaningful profile of you. The major exception to this is Facebook where they profile you based on your personal posts and activity as well as all your friends.
Facebook and Google have a global reach. They have trackers and profilers on about 80% of the web sites.
Google and Facebook have a global reach that few others can duplicate. Google has trackers on 80% of web sites and probably 80% of phones too since Android is completed compromised by them. With all this data, they may know you better than you know yourself.
