This was recently justified to me in an interesting way. Back in the heyday of print newspapers, you had your subscribers, who had the paper delivered every day. Then you had your casual readers who would pick it up at a newsstand if they saw an interesting article.

And then you had your "freeloaders" -- the people who would read the paper at the library or fish it out of the trash or would ask to borrow it from the person on train next to them.

These links are basically for the freeloaders who would never have paid anyway.

Interestingly enough, most US libraries actually offer way to read these things for free by going through the library website, it's just not as easy as using an archive link.