A couple of thoughts
I'll start with "The Rise and Fall of the Emma Gees". That pamphlet keeps recurring because machine guns became ubiquitous. When they did they became the infanteer's personal belt fed rifle and employed at the gunner's discretion. They lose much of their effectiveness that way. Fire discipline, ammunition consumption, priority targets, mutual support, concentration of fire, etc - all of that is lost over time. Muscle memory fades. Maintaining a small MG platoon in the battalion as a Centre of Excellence probably has as much or more value than its actual tactical value.
At its best it provides MG advisors to Coy and Platoon commanders on how to get the best out of their assortment of GPMGs, LMGs and Automatic Rifles.
Although the weapons are universally distributed for carriage somebody needs to be maintaining a plan on how best to employ them as the CO/OC takes his command into different situations.
I suggest the same thing is true for mortars/artillery starting with hand grenades, 40mm-51mm-60mm-81mm-120mm-155mm and other HE launchers.
It is also true for the Anti-Tank Plan managing AT grenades and 40mm-66mm-84mm-120mm-127mm-152mm HEAT warheads.
Some of these weapons are "specialist" weapons. This is particularly true of the older systems. Newer systems don't require the same degree of operator training. This is good and bad and replicates the Rise and Fall of the Emma Gees.
The old time specialist operators knew not just how to operate their systems but also their strengths and weaknesses and how to get the best out of them.
This is not a new problem. And, again, I suggest that history offers guides. In particular the mock battles of the Fort Henry Guard.
Each man in the 24 man platoon is issued 60 rounds. He doesn't own any of those rounds. Those 1440 rounds belong to the Lieutenant leading the platoon. And he gets to decide how to group his weapons and where and when to discharge them. The fire discipline is more akin to a modern artillery unit than a modern infantry unit. I suggest that that same fire discipline needs to be employed with the modern infantry's support weapons. Section may only have half a dozen 84mm rounds or 2x 127mm Javelin rounds. But the Platoon Leader has 6 Javelins and 18 to 24x 84mms. The Coy Commander will have 18 to 24 Javelins and/or 54 to 112 84mm rounds. And those rounds can be selected depending on the target set anticipated.
Some of the lessons of the Emma Gees also apply. The Irishman in the Anti-Armour video talked about the value of Key Holes and using terrain. That is also known a "enfilade from defilade". Taking the enemy from the flanks while protecting your own flanks. Fire and Retire. Masking your signature. Obscurants. (In ancient days we didn't carry HE for the platoon mortar - we carried smoke and a couple of flares)
These lessons, I suggest are common to all Direct Fire systems, including the rifle.
Second thought
The cost of the Javelin - The capital cost of the Javelin is apparently somewhere in the 80 to 150,000 dollar range. About the same as most large calibre ATGMs. Pricey.
But what price FJAGs Excalibur, or even his cheaper guided systems?
For that round to be delivered to that grape hut the following is required:
The round,
The gun,
The truck,
The ammunition limber or equivalent
The crew
The GPO
The FSCC
The FOO
The Pl Leader
The Section Leader
A lot of dollars and time.
The Javelin may cost a lot of dollars but so does a manned battery of guns with rounds on hand. And delivery of the arty round takes time. And a second or third shot may be needed depending on how successful the game of Chinese Whispers was in relaying the target co-ordinates. And assuming the enemy hasn't moved by the time the first round arrives and stays around for the second round if the first round fails.
The Javelin, on the other hand, is immediately available, accurate, and effective.
Reducing the price of the effect is, of course, desirable. And thus CG84s, AT4s, NLAWs, M72s, 40mms and, I suggest, in the near future the provision of the 70mm APKWS vehicle mounted missiles which were developed as a cheaper supplement to the TOWs and Hellfires. And which could be mounted on the back of a MRZR.
As the guy in that field being shot at I would sooner have the solution to my problem in my hands than have to rely or my radio for timely assistance.