Fire support did not help the U.S. platoon because there wasn't much it could have done in the few minutes. Calls for artillery fire are slow and calls for company mortar fire not really effective against an assault gun and dispersed infantry.

No opponent would always "know" that the line of defence is reverse/counter slope, for there are usually several slopes and the first one could be largely a decoy. German defence doctrine advocated a deep defence which had a zone for skirmishing and delaying in front of the real deal. There were often even two fully prepared defensive positions plus if possible decoy positions. The secondary defensive position was a necessity against Soviet offensive preparatory shelling, and the Soviets rarely kept both positions under simultaneous fire.

You do not increase the uncertainty for the opponent by presenting your troops in the showcase.

Besides; forward slope defensive positions are easily detected, thus never an advantage from a detectability point of view. A defensive position that's well done does not tell to an aerial photo interpreter what's decoy and what not.
Reverse slope defences on the other hand cannot be observed permanently like forward slope defences and allow thus for much less reconnaissance by the enemy.


JMA; the key is -as so often- that I wrote about capable opponents. Some dinosaur calls it METT-T. The "E" stands for "enemy". Forward slopes defences ARE suicidal against capable enemies. I doubt that the Rhodesian army cared much about capable enemies. It didn't fight one for a generation in the 70's.
The WW2 booklet in question was about a war between first and second-rate powers. A forward slope defence was suicidal in that war. Even Romanian infantry regiments of '44 and Italian Bersaglieri of '42 were capable enough to rip forward slope defences apart, even the ones set up by the Argentinians in '82.


I know many gimmick and have added some gimmicks* to counterslope, reverse slope and ridge defence positions. The forward slope on the other hand is simply hopeless.

*: One gimmick is for example to set up an additional concealing screen (a fence of netting, for example) a metre ahead of the ridge in order to increase the survivability of the ridge defenders and observers. Gaps created by shelling can be plugged with the concealing "umbrella frame" trick of snipers, even in the midst of a fight.
This gimmick solves a problem which occurs on very straight ridges; the problematic silhouettes of the defenders.