I have said this in the past, and I will say it again: Damage indicators and armorstatusHUD are like hacks.
Hacked clients help players in mainly two ways: they assist the player in doing what they are doing, often in ways that no human player can replicate, and they also give the player information that they would not otherwise have.
Let's look at the second part, giving players information that they should not have.
Where do you draw the line between fair information and unfair information? X-ray and playerESP are obviously unfair, so what makes them different?
The difference lies in that the information the player gets are difficult or impossible to obtain otherwise, and that they give the player too much advantage over others.
Let's see if that classification is correct:
Optifine zoom is generally regarded as fair, and the information players get from the optifine zoom are usually obtainable through other means, like turning fov to minimum, looking closely, or walking up close to check. You also do not get extremely useful information, like what enchants they may have on their armor, or what other items are in the player's inventory, etc. Therefore, optifine zoom is fair. The other part of optifine, improving performance, is also fair, as it is like getting yourself a better computer. That gives people with less powerful computers a better chance, as fps is extremely important in pvp. It is not an advantage that other players cannot obtain, so it is also fair.
Equivalent hacks: most hacked clients already have optifine installed to boost performance, so there is no hack for it. No client without optifine felt the need to add a telescope hack, so optifine zoom obviously does not give a big advantage.
X-ray resource packs are unfair, as they allow players to see ores, mine extremely efficiently, and it gives a massive advantage in gear. No player should ever have such an advantage.
Equivalent hacks: x ray and cavefinder (good xray resource packs have the functions of both).
Let's analyze what damage indicators could do for you:
Tell you your opponent's health and potion effects. Potion particles are usually hard to see and identify in the heat of battle, and often when you realize the other person ate a golden apple and you did not, it is too late and you are dead. Health is impossible to see under normal circumstances, and it allows you to pick fights better, avoid people with more health than you, while you will know who is weak and who you can pick on.
A floating number particle on a person whenever they gain or lose health. Incredibly useful, as it is basically a weaker version of playerESP, since you can see the particles through the walls. No one can ever hide from you to regen, and if there is a fight going on anywhere in the map, even beyond normal nametag render distance, you will be able to see it.
Equivalent hacks: healthtags, playerESP
ArmorstatusHUD:
Allows you to see your armor durability. Usually in battle, people have to go into their inventory to see. They would have to stop fighting for a second or two, and the information they gain will not be precise. They would not know exactly when their armor will break because they cannot check too often. Hovering the mouse on the armor to see exact durability takes too long, and for protection enchanted armor, the number doesn't mean much.
On average, a player with armorstatusHUD will get new armor on when an old piece breaks twice to three times as fast as a player without the mod and instead relying on the sound of their armor breaking, or their armor bar decreasing.
Equivalent hacks: some clients have an armorHUD hack, most only have autoarmor, which is slightly better than armorstatusHUD
From that analysis, armorstatusHUD is already pretty unfair, but damage indicators are basically equal to hacks.
