You can dress the monkey in silk and still will remain a monkey

[Agemnon]

^Good luck trying to tag the mobs quickly enough to get credit. :B

This right here is the competition. Guardians and axe 5 warriors are great for these kinds of events. Thief on the other hand... can work, but we need to time our dagger storms at the right moment (i.e., wait for big nukes to be blown on wave 1 then DS on wave 2 or 3) and use a stopwatch to keep track of when certain mobs will render so we can shortbow 2 accordingly.

[Cariad]

How so? What's the actual competition? Is this due to intention design or some bug that doesn't reward everyone?

In Orr, Cursed Shore particularly, most of the farming spots are quite ferocious competition, to the point where if you're not in a party, you wont be getting any loot at all out of 150+ mobs (of course I still get loot when I'm solo because I'm uber pro, but not everyone is!)
But yeah sometimes you wont. You basically have a bunch of parties camping at the spawns, so as soon as the mobs appear, they're gone. If you're 1 second too late in firing your skill, or mis-judge it as a slow caster, you have to wait for the next wave. It's usually easy to get a gold in the event (besides the defend the perimeter one in the Plinx chain, which can be trickier as there are nowhere near enough mobs for it - massive scaling issue here) but loot is another story.
Lots of people don't rez downed players (why would they, they're level 80 with ten million skillpoints and they're not getting any lewts!) and yeah it's all just a bit of a greedy place in general. I imagine this sounds horrid to you haha. Well to anyone in fact, but I imagine this describes your vision of e-hell.
It's not always that bad, just a bit shitty sometimes.

[Agemnon]

so as soon as the mobs appear, they're gone.

Unfortunately, if you can see them it's too late, you have to hit where they're about to render, since their game data uploads before their graphic.

[Cariad]

Unfortunately, if you can see them it's too late, you have to hit where they're about to render, since their game data uploads before their graphic.

Yeah. Got to love how I can spam the auto-attack key at the approaching mobs, only to see 'Invulnerable' and their hp not going down, then as soon as they become vulnerable, they disappear.

[Agemnon]

Yeah. Got to love how I can spam the auto-attack key at the approaching mobs, only to see 'Invulnerable' and their hp not going down, then as soon as they become vulnerable, they disappear.

Oh that's Penitent, hardly anyone goes there anymore despite it actually being better now than the previous patch.