I think you should read all the comments to that post.
Ours most definitely does only heat up to a certain temperature when on a lower setting, and firmly stays there.
I think what's happening with many of the newer vs older crock pots is the fact that the newer ones control the element differently (IE, "on or off", no in between) and the electronics cycle that element on and off as required for it to maintain the temperature. Older crock pots will often have a rheostat control that simply provides less voltage to the element and maintain the lower (but often less configurable) temperature via a different method.
I do know for a fact that when my crock pot is set on a lower setting (keep warm, or low) it most definitely will never surpass a certain temperature. On more than a few occasions we've set things on low only to have to crank them up in the last hour or two of cooking (after 6-8 hours of cooking by that point) in order to actually avoid eating undercooked food - it was just not getting hot enough.