It’s not that they didn’t name the source, it’s that they (by their own admission) didn’t corroborate the story. They had an unnamed source who claimed document

It’s not that they didn’t name the source, it’s that they (by their own admission) didn’t corroborate the story. They had an unnamed source who claimed documentary evidence existed, but nobody at buzzfeed saw any of it. Combine that with Buzzfeeds pretty obvious slant on the issue, and Mueller’s refutation of the story, and it comes out looking terrible for Buzzfeed.