Being required to be connected to the EGC does not have emotion or physiological need in it.
But if it needs a ground, it requires action on our part. And that action must be code compliant.
There is no existing Code Rule that retroactively removes cable armor from the list of effective grounding means in previous editions of the Code for installations assembled under those previous editions of the Code. Show me otherwise.
I am loathe to speak for "They", but "They" apparently "intended" to keep existing installations of non-bonded AC classified as effective grounding means because "They" were silent about retroactively reclassifying existing installations. "They" did not choose "to eliminate it altogether," as you claim.
Then please show me in the current code where the old AC cable is listed as an effective grounding means.
We are installing a new fixture on an old system. This new fixture has a ground that must be connected. We have to connect it per the code. So let's follow what the code says:
410.40 General. Luminaires and lighting equipment shall be grounded as required in Article 250 and Part V of this article.
OK so now what does article 250 tell us?
250.4(A)(5) Effective Ground-Fault Current Path.
Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a low-impedance circuit facilitating the operation of the overcurrent device or ground detector for high-impedance grounded systems. It shall be capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be considered as an effective ground-fault current path.
So we can't just connect to anything. We must connect to an effective path. The old armor has been shown to not be an effective path by testing and as evidenced by the change in the type construction.
Let's now look at what part V of article 410 has to offer:
410.44 Methods of Grounding. Luminaires and equipment shall be mechanically connected to an equipment grounding conductor as specified in 250.118 and sized in accordance with 250.122.
Exception No. 1: Replacement luminaires shall be permitted to connect an equipment grounding conductor from the outlet in compliance with 250.130(C). The luminaire shall then comply with 410.42(A).
So we are required to use an EGC as specified in 250.118 and of appropriate size so let's look at that:
250.118(8) Armor of Type AC cable as provided in 320.108.
320.108 Equipment Grounding Conductor. Type AC cable shall provide an adequate path for fault current as required by 250.4(A)(5) or (B)(4) to act as an equipment grounding conductor.
320.100 Construction. Type AC cable shall have an armor of flexible metal tape and shall have an internal bonding strip of copper or aluminum in intimate contact with the armor for its entire length.
250.122 Size of Equipment Grounding Conductors.
(A) General
...Where a cable tray, a raceway, or a cable armor or sheath is used as the equipment grounding conductor, as provided in 250.118 and 250.134(A), it shall comply with 250.4(A)(5) or (B)(4).
So if we choose to use AC cable, it must have an adequate path. We can't just use any old path we want. The old AC cable did not have an adequate path. The AC cable with an adequate path has the bonding strip.
We could use a different method:
250.130 Equipment Grounding Conductor Connections.
...For replacement of non?grounding-type receptacles with grounding-type receptacles and for branch-circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch circuit, connections shall be permitted as indicated in 250.130(C).
250.130(C) Nongrounding Receptacle Replacement or Branch
Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates
(4) For grounded systems, the grounded service conductor within the service equipment enclosure
(5) For ungrounded systems, the grounding terminal bar within the service equipment enclosure
Or we could use GFCI protection. From 410.42
Exception No. 2: Where no equipment grounding conductor exists at the outlet, replacement luminaires that are GFCI protected shall not be required to be connected to an equipment grounding conductor.
None of the alternatives show where the old AC cable with the faulty ground path is allowed to be used for new connections to the grounding system. It used to be there as an acceptable path, now it is not. If it used to be there, but it is no longer there, it has been eliminated as an acceptable path.