Lately I'm noticing how comments are actually a tool for tracking and profiling. You see kids, there used to be a time where you could comment on a website just by putting a name and usually an e-mail address too. You went, typed stuff, that was it.
But now, for commenting, most websites require you to have an account. Many pages also offer an option to login with e.g. Google or Facebook. And of course, there's trackers from those same pages. So they can learn from you wherever you speak.