We'll file this one under "rumor" even though it makes a whole hell of a lot of sense. Some sources near to Kotaku said that Warner Bros. knew how bad the PC version of Batman: Arkham Knight was for months but still decided to release it when they did.
“I will say that it’s pretty rich for WB to act like they had no idea the game was in such a horrible state,” said one quality assurance tester who worked on the game for years. “It’s been like this for months and all the problems we see now were the exact same, unchanged, almost a year ago.”

Two sources, requesting anonymity to avoid jeopardizing their careers, spoke with Kotaku over the past week in hopes of explaining how the broken PC version of Arkham Knight made it out the door. They both said that Warner Bros. was aware of the many issues facing Arkham Knight on PC and that the publisher chose to ship the game regardless, not to maniacally screw over customers—but because they believed it was good enough.

The anonymous sources continue on...
In various meetings, QA teams were told the new consoles were “not nearly as easy to work with as [Rocksteady] expected” and testers should focus time on finding console bugs. This particular team was made up of roughly 100 people, with about 10% focused on the PC version.

“We reported literally thousands of bugs that were specific to the PC version relating to the frame rate,” said our QA source. “All sorts of fucked up texture issues. The Batmobile in particular has always fucked things up on PC.”

The sources go on to say that some testers reported more than 100 bugs per day. They also note that they were bug checking specifically at 720p resolution most of the time, thus providing another good reason for the performance gap on those on PC trying to run at "normal" resolutions for modern desktop gaming.