Or you get one of those mail saying "We are removing you from the list because you don't read our newsletter", often without offering any other confirmation signal. Basically they says "Let us track you or you are out of this list".
And this is also the result of marketing people who look at ways to increase the "good numbers", more likely to show to their bosses. They don't actually care if you read or enjoy their content, you are either one of the users who increase their opening and click rates, or you're a useless burden to them.