Legit or no? - Fighting glitched bosses.

It's NOT "legit" because it's not how it's intended to be played.

What's Nexon's intention regarding "glitched" bosses?
"glitched" portals?
"glitched" skills?
"glitched" exp:hp ratios? (train in NLC/world tour? I hope not)

There are glitches in this game that have existed for YEARS, often inseparable from extremely desirable content. Nexon's intention as you put it clearly has little to no control over the game we play, so why have such reverence for your assumptions about it? To entirely avoid these glitches is an incredibly undue burden on the player.

Czak is a good example, lets look at some of the ways czak has been borked over its history:

Dispel spam from dispel arms, since Nexon didn't separate the normal attack from the dispel attack on at least one.
Failure for individual parts to aggro and attack unless attacked (or at all)
Body dealing no damage

Tell me, do you know a time when not one of these glitches (or others) was occurring? Only recently! Maybe - I still hear reports of aggro fail. So all "legitimate" bossing had to wait until the boss was pitch perfect compared to what you assume Nexon's design for it was. Any czhelm was illegitimate! Why should the incidental nature of whether they did it repeatedly or once matter? They knew it was glitched and they still went!

It'd be swell if Nexon's design didn't vary the time or ease it takes to kill these bosses, but how do you know what the intent was for "how long czak should take" when the original form was different than what we fight now? Not to mention the countless rebalancings that affect player damage occurring at the same time.

It's pretty straightforward that Nexon's "intent," in story design, is that there are big bad evil things that threaten the world, and heroes kill them. Once. Guess that time you killed the tree of hell twice in one day was a glitch, oops.

Oh, are you going to say that glitches that make the boss harder rather than easier, as dispel spam did in the early days, are not illegitimate? If that's the case, your only rational argument is that glitches are bad to the extent they increase supply in the economy (or the imagined economy if the glitch has always existed). If economic distortion is your measure, Nexon made the game utterly illegitimate the day they released potential. Their input is no longer authoritative by your own reasoning.

I get that you don't like it when things you achieve are cheapened. But you can't expect players to not experience content that is flawed. Most of the game is flawed.

Where my line is: do not hack. Do not use external programs on this game - even when they do no harm standard and merely repair broken content to a functional state.

But if Nexon makes a feature available to an unmodified user, however screwed up, enjoy it. Because that's all we're going to get from them.