Couldn't disagree more. The lats act as a shoulder FLEXOR in the bottom position of a bench, IF there's sufficient tuck and external rotation. In turn it potentially yields huge pop of the bottom, which is why the raw benchers always speak highly of the importance of strong lats.
Now, flaring out too much WILL put the humerus in internal rotation and you'll lose the much of the tricep and lat power.
Tuck and external rotation are absolutely not one and the same. The bend the bar cue, when done properly, forces external rotation and maximal lat involvement.
Trust me, I bench almost entirely with my lats, upper back, and delts. If you only tell someone to tuck their elbows and don't get them to activate their lats, you're doing them a huge disservice. Telling someone to tuck will NOT create external rotation torque, nor will it engage the lats/upper back.
Telling someone to bend the bar will create external rotation torque and engage the lats. And who cares where the elbows are if the socket is safe and the musculature is engaged? Fyi, the elbows will be slightly, but not overtucked.
Try this at home, put 90% of your 1RM on the bar, grip index finger on the rings, and bench with your upper arms pinned to your ribcage. If you can complete that rep, then I can coach you to a new PR in two minutes. I know this because I've done it several times with my training partners, all competitive powerlifters.
If you really want pop from your lats, bench with a shoulder width grip and tuck hard.
Here's an example of proper elbow positioning, something I had to learn by not worrying about my elbows:
http://youtu.be/I7RAduOFS3Q