Upon reading your reply I have come to conclude that you are indeed referring to an increase in survivability across all damage, and not specific sources of damage. Your position is based on how damage from all sources affects survivability. Furthermore, I agree with your belief that as a game continues the value of armor typically diminishes.
At this point however, I begin to disagree. The reason that armor diminishes is because of the increase in skill damage, not because of the mechanics. If you are fighting a demigod that focuses on skill damage (i.e., Torchbearer) armor is of very little use to you. In contrasts against an attack build (i.e., auto-attacking Regulus), armors value never decreases.
Your view on dodge is mostly congruent with my own. I have some slight differences in interpretation, however given the relative rarity of dodge items, it doesn't amount to much.
At this point, however, I must object and be insulted by your claims. You reference me to a spreadsheet which contains the effect of armor upon mitigation. Furthermore, as you point out, this is a relatively simplistic display of the effect of armor created to provide a simple understandable guideline. I object because if you had consulted, even briefly, the link to the post I had provided (presented again here: https://forums.demigodthegame.com/365017 ), you would have found that it contains all of the information you presented in table form at the very top of the document. Furthermore it goes on to perform other calculations that are relevant to Demigods because they were perfomed using the Demigod data and formulas. Additionally, not only am I familiar with the post, but I wrote it. Hence I would suggest I am somewhat familiar with the underlying relationships. While I may disagree with your presentation, I have considered all of your points and evidence. I feel it poor behavior to not have the same consideration in return.
Regardless of all of this, the point is that the worth of armor decreases because of the increase in skill damage.To evaluate the worth of armor in regards to overall survivability would require not only examining the effective value of armor versus hit points versus dodge, but also involve increases in damage dealt. As the truism goes, in many cases, the most effective defense, is a good offense.
I agree that (virtually) no one cares. This board is filled with people that are busy not caring, reading, or thinking. However, you do represent a portion of the board that does have the ability to listen, think, and care. It has been a continous annoyance that people are allowed or perhaps encouraged to represent themselves without dignity or tolerance for others. However, this isn't the place for that discussion.
If we want to generate a general rule upon the worth of items, it seems that something regarding specialization would be appropriate, based upon level. That is to say, in early game focus on survivability, hit points, armor, speed, and an adequate level of mana regernation. Buy the most cost effective pieces, as many as possible. In late game, switch to offense, mana (for skill damage), +damage & attack speed if you auto-attack, and speed. I haven't done enough work on this to be ablet to say anything concrete, however if we are creating general rules this seems to be the better path to take, rather than to just say only get X units of armor.