A) The Economist says that article limit is 5 per month. But they waive that limit for Google Crawler. So they mislead search engine into thinking that article is accessible, when actually it is not. They intentionally misrepresent as a free service to attract free SEO traffic.
B) The person who shared link to that article was not aware people like me will not able to read it. They were also mislead into thinking is an accessible resource, to get free shares.
C) Even if you don't have a problem with A and B, their UX is ridiculous. One message to subscribe is covering another message to subscribe. As the same time there is a newsletter popup which promises you a PDF.
I hope that now you better understands what annoys people. It's is not that business are trying to make money; it is how they approach it.