Considering feeding from mana wyrms disgusted a set of blood/high elves which were then exiled, and the fact that draining from demons was a taboo/caused revulsion with Silvermoon aligned blood elves in TBC…
Yeah. They shouldn’t be bragging about this in the open.
Ultimately both races are descendants (or rather corruptions) of a species of pure magic. Their calories are basically mana.
With all these Old Gods, Banshee Queens and edgy BElves destroying their mana source they’ve adapted new methods. The new sources have very noticeably influenced how they use their magic.
NElves sustaining off big trees tend towards nature magic (more balance druid than mage) so any using simple arcane magics are your traditionalists / highbornes trying to cling to their once held power.
Nightborne had no reliable source so they rationed it across their “class” system in the form of Arcwine and leylines. The poor were left to starve and go mad. The rich (who had way more than they needed aka subtle Blizz class commentary) basically isolated themselves in a walled city and spent their finite resource on experimentation so their knowledge of arcane magics is probably the best of all mortal races.
HMs:
BElves using the Sunwell and siphoning magic are basically pretending the be High Elves but are actually far more suited to unstable fire magics.
VElves studying the balance of light and void are 100% Sh Priests.
I think it’s worth pointing out that the Shen’dralar spent the last 10k years in entropy and stagnation with a continuing shrinking population that abandoned most of their old city just to get their next magic fix, and by the time of vanilla they’re a small group less than a thousand elves standing even before the Horde wrecked dire maul killing the majority of the remaining elf population, Maiev’s killings and then the fourth war/any other crazy world ending threat. So they’re a very small group number wise. They didn’t really have the opportunity of magical innovation compared to the nightborne that kept a much larger society running behind the shield where they kept innovating in their own bubble-universe. Which then again can be seen when the shen’dralar recently rejoined the world back during cata as the blood elves are making fun of their archaic ways of magic that they counter. Not to say that they don’t have powerful old knowledge that can be considered lost/unknown, just that overall their way of casting magic is a bit dated.