I sympathise, it's happened to many a prolific poster, I've made some really good posts that have be been totally lost, so demoralised by it, I think I didn't post for a while, sometimes even days.
Ah, but my point is that it is the actual use of magic that further prolongs life, boosts immunities, further boosts intellect even more so than just the passive proximity or passive natural connection to the Well of Eternity. The night well is a powerful magical elixir they can do a lot more amgic with it too - id on't know if there is a minimum threshold of magic required to prolong your life indefinitely - but I do know the night elves did this before the sundering via using the Well of Eternity. From t his I deduce that the magic using night elf populations like the Shen'dralar and Nightborne could do this with the various magical sources they utilised (Immol'thar's magic siphoned and filtered through pylons in the case of the Shen'dralar and the nightwell in the case of the Shal'dorei)
I would think the goblin example only proves this even though it's an entirely different situation, kajamite seems like a drug - not a cosmic magic DNA altering power and the goblins are not made from it unlike the Night elves. Without kajamite they just got cravings and are less sharp. Think of kajamite like a constant intellect potion they can take to boost their functions. They don't devolve persay, although we wouldn't know, they seem to be able to constantly supply themselves with it.
And while blizzard mentions the weakening of the exile, it's never included all the symptoms in the same senstnce - I can't think why every other passive enhancement of the Well of Eternity is lostbut not intellect. The loss of the intellect boost I have never felt made the Thalassians simple, I think their intelligence just dropped to human levels or slightly above, rather than much higher (on average) that the average night elf population would have. This is ofc boosted up again passively through the the Sunwell and again furthermore by utilising the arcane magic, same with their longevitiy and stature - which is why they stand on average a 6'6.5 whereas humans are more like 5.5 to 6'. So it goes back up again to the extent that with the double enhcancment from the sunwell, the average Thalssian is more intelligecnt than the non-magic using Darnassian, but not moreso than the magic using one -
Intelligence is impossible to measure, so I just talk in averages, at the end of the day, no matter how intelligent an elf is , a human can be born with similar o, comparable intelligence anyway - I just think that an average the elves have the higher intellect, and then those who handle the arcane even more so. As all blood elves use it in some measure, they have the double boost, with mages able to stretch that even further.
The instance of the blood elf mocking the night elves for using outdated magic happens in zone Azshara, when you level a horde and do that zone. However the context the horde player doesn't have is that the Night elves they are fighting are novices completely new to magic or former highborne who'd abstained from using the arcane in line with the Kaldorei ban on it during the Long vigil period and had recently picked it up with the lift on the ban and the alliance with the Shen'dralar. Now you don't meet the Shen'dralar, you meet the new highborne, darnassiasn who've only been using the arcane for a few weeks - some for the first time since nearly 10,000 years ago, and some for the first time ever -
They are not going to be seasoned mages though, they would be using some techniques from a long time ago - what likely has happened is that the Shen'dralar have tasked them with teaching some of the newbies, and in turn teach them.. however there hasn't been much time for training. The cataclysm has just happened, and the Shen'dralar have only just rejoined with the Darnassians, and already the ones at Talendris point are off to fight - they'd be relying on a lot of knowledge from 10k years ago - making it easy for a seasoned mage at combat to exploit.
What it isn't an indication of is that the night elves are more stupid than the blood elves.