Two reasons come to mind, one historical and one practical: First, the pingback implementation in WordPress was one of the more common vectors of WordPress' en

Two reasons come to mind, one historical and one practical: First, the pingback implementation in WordPress was one of the more common vectors of WordPress' endless parade of security vulnerabilities. I remember years ago it was common practice to disable pingbacks (or even rip out the code) as a security precaution. Second, pingbacks direct readers away from the site. This is good for readers and the online community as a whole, but bad for online publications which want to use comments as an "engagement" tool.