It's a tactic, the only the latest of many, to go after people who use Facebook to communicate without paying for ads (that is to say - without paying current auction prices for the attention of the recipients of their messages.)

Isn't it funny that every change to "protect users" ends up with you paying Facebook more to reach the people that followed your page?

I still remember when Facebook Pages were promoted as an alternative to feeds and newsletters. You could follow a page and be sure to receive all updates from them. Now you even have to pay to share links.