Because people don't read microcopy, and the designers of that subscribe widget know that.

A lot of people, when faced with that box, will miss the "continue reading" button and assume they have to subscribe to finish reading the article.

It’s not “micro copy” even on a phone it’s a normal font size and saw it immediately.

Is “dark pattern” the new “monopoly” on HN - ie “anything a company does that I don’t like”?

Microcopy doesn't mean small in terms of font size: https://uxwritinghub.com/what-is-microcopy/

Dark pattern is a well defined term too: https://en.wikipedia.org/wiki/Dark_pattern

I've responded to other similar comments, but there are a few things which I think make this a dark pattern: the modal pops up after scrolling far enough down that you’re absorbed in the content, the “continue reading” is not styled as a button, and is accompanied by a chevron to the right which implies navigation away from the current content (I want to scroll down, not go right).

I agree there's a bunch of people who call anything they don't like a 'dark pattern', but I think this crosses the threshold for 'dark pattern' to be a reasonable description.