The US Navy F-14 and S-3 use DLC as described, including the button on the control stick to actuate the DLC.
In some installations, arming DLC after landing gear and flaps are extended raises the spoilers on the upper wing surface a small amount. That becomes the basic landing configuration. DLC can then be used to increase lift (reduce rate of descent) by retracting the spoilers, as well as reduce lift (increase rate of descent) by extending the spoilers further with little or no pitch or power correction.
JF:
I'd vote for the use of spoilers in gliders in the landing pattern as a valid implementation of DLC. I was taught to fly the landing approach in the glider with spoilers set half open as a baseline, then using the spoiler lever as a "throttle." The control stick is still used "in the normal way"...
Since lift IS "controlled directly" by means of the same type of control surface (spoilers on the wing), there is no reason to disclaim the glider implementation. The lower-surface spoiler serves as a balancing device, reducing actuation loads as well as required pitch changes.
It makes no dofference to me whether the actuation device is a button or switch on the control stick or throttle lever, or a separate lever in place of the nonexistent throttle lever!