Agreed. Mainly because I've been to Brayflox HM at the iLevel you suggested before along with 3 others of similar iLvl. And we won without any wipes at any point, though it was a much longer run than a very slow City of Amdapor run. It simply goes back to the statement the JP blogger made on a lesser scale -- mechanics, player coordination and actual player proficiency in their job will dictate their level of success. I have no doubt in my mind if the other three players were bad at their job then we would have never won, even if we were all i70 instead. To that end i70 is the obvious cutoff point despite it being tuned to i55.
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I just recently got back into starting to do endgame (aka catching up) and I must say this. The OP is spot on. To preface during 2.0/2.1 I played on my legacy character and got as high as T4 with semi-constant winning basis with my static. No T5 up to that point, no Primals (big mistake on my behalf). Around the time when 2.2 came out, I restarted on a new character to attempt to fully learn the mechanics behind playing WAR (as well as being named after an all so famous Dragon Uppercut). I then realized what this JP blogger realized -- beyond your own personal proficiency, this game is geared around very unforgiving mechanics. To that end, it simply does not matter if you have Echo, or at a much higher iLvl than what's needed. You simply require 6-7 other people who can successfully perform their roles with any given mechanic thrown at you.
I just yesterday cleared Titan EX, but not without going through countless attempts (about 80 if you were wondering). I picked up exactly what to do in about 6 attempts, and it took me another 5 attempts to fully tune myself to the tune of perfect tank swapping and also tank swapping with Echo over 15% (which can be a problem). Then another couple of attempts to understand what to do during Gaoler phase (in the parties that could actually GET to Gaolers). I'd like to say as tank I fully mastered the fight relatively easy and could have done it as soon as it was released in 2.1. However, this does not speak well at all for everyone else, mainly the DPS. Countless times people would get knocked off or even take full stacked weights of land right to the dome, killing them instantly. These were people of varying iLvl, people who were sub i90, people who were reaching or just beyond i100, people geared in Levi gear (hence beating Titan already), people who were geared post T6/T7 and everything inbetween. It's more so depressing when you realize that Titan does the exact same routine every single time, the only real randomization being who gets targeted for landslides if DPS are in the process of breaking others out of jails after Upheaval. Despite this, people still get knocked right off/killed every single time, usually to the exact same exact mechanic that killed them in the previous fight. To this, some are actually happy that they get MORE Echo after wiping. Why? Echo doesn't help you avoid taking a landslide to the face, you'll continue to lose despite whatever Echo you get. After tens and tens more of fights, I finally won yesterday in a party which averaged about i93 overall (under Echo of 10%). The first two attempts we lost actually being my own fault in the end (incorrect tank swaps making the arena lopsided for 5-way landslides across bombs).
As soon as I did my first couple of fights, I proclaimed to my girlfriend next to me, "this is now my favorite fight in the game." Simply because how unrelenting it is as well as the fact that it completely ignores Echo applications and otherwise makes the fight harder with applications over 15%. It's the only fight (so far, for me, I know about Levi EX and T5-9) that forces everyone to play their roles under an unforgiving mechanic that completely removes you from the fight. I still believe that it will be my favorite fight after the fact as well. To this end, I can't wait to do further content beyond this point, as I'll find some of it very enjoyable. To the reverse, I agree with the OP in so far that every fight shouldn't be so extremely unforgiving. There should be a few fights that at least allow for some sort of recovery phase instead of "one death we're done."