DATA POINT:
Applied a few weeks ago for the Business card. I've had one from October 2014 until September 2015, that's closed now.
Got pending message and app id, called in and they said they couldn't approve it but couldn't give me a reason. Got the letter with the "too many accounts" as reason for decline.
I called in to ask how 3 low limit CC accounts is too many, and they brought up that they see my cancelled card from 9 months ago and that played in to the consideration. It looks like they now keep much closer track of all activity.