Oh, ofc, it's not that you need them to win with most things, it's that if you take them you're 100% sure you'll win regardless of whatever else in about 10-20 minutes. So if you're looking at completion and PQI with badges and wonky class/race stuff, this can shave off a day easily. I mean I did a dwarf monk of JJ in Namtar's for the lols, but that took 2 hours and 4 tries, with pissorff you could practically rainbow either/both in less than an afternoon (well apart from VS Monk, Vampire, and Warmonger). It's kind of how most people just use the Vampire to do VGT once, because failed attempts can add up in time and you can spend a day at the computer not having actually done anything, while you can spend 20 minutes and have 9999 gold.
The whole "those two places could use a nerf" thing was really an universal sentiment, there's a thread about it (or even two) buried in the forums, but the search doesn't work so I can't find it now. I think Wald0 started it (not sure though) back when he said, after a full rainbow everything, that Vampire and Monk Vicious Steel runs were the last and most difficult runs in the whole game (by far). I whish I could dig up the thread I found it when I was having trouble with the monk, and I can't find it now, but you kinda get a who's-who of us vet beta testers all kinda sure that there's no chance VS doesn't get a nerf after the last Vampire tweaks and the Trisword Nerf (and the Monk rework before that also figured into it, it's very obvious he wouldn't have problems with that place before that and now it's insanely difficult. He used to have 50% magic resists and more damage when that place was originally made, and there was no Blah Blah in it XD And he couldn't even do Ick Swamp when vampires did magic damage afterwards, VS for him is just unfun and plain unfair to the extreme).
I whish I could dig that thread up, I remember actually finding it on google, but it's not there anymore, and somethign's way off with the forum search. Back when VHoS (what it was called) only had the Indomitable in it, people seemed to find it fun and we didn't have a clue about the DR exploit, because we never went looking for anything to help out. But when the devs plopped Blah Blah in there without adjusting anything, and what with his ridiculous stats - everything about that place just turned to exploit exploit exploit cheeze cheeze cheeze, and the aforementioned nerfs and reworks caused some runs to be just plain messed up like nothing else in the game is. And then when the overall difficulty was lowered in the entire game following those last nerfs and reworks - nothing at all was done about VS (probably because it looked like we were running through the place easily, when in fact the vast majority of runs in there ammounted to basically exploiting glitches).
Namtar's only problem is that Binlor/Pissorf is just so obviously helpful for peripheral reasons (cramped map, magic resistand high dmg boss), but using him ends up evading a ton of stuff that actually makes it a difficult dungeon (to any degree). You get to spellcast against a 110+ dmg, low health, debuffing, 50% magic resistant boss in a way which also evades blink and resists on the rest of stuff, it's not that you have to do it, it's that it just makes too much difference. You don't have to prep it with the intention to cheeze, just declogging the layout is an innocent enough reason to want to prep Binlor there, but what you get bundled with that bit of life-quality improvement accidentally also nullifies the dungeon almost entirely. It's more unfortunate than anything, if the place was less tough and nasty looking to any other approach, there'd be fewer ways to stumble onto cheeze mountain. It's just got that countereffect thing going on where all that's supposed to make it difficult accidentally ends up causing you to just bypass it instead of best it... Btw, I beat it with VT lvl 1 bosskills with TT rogues and no spellcasting. When I came up with it. For a while used it for all my vids with anything. Just to remind Tinker that I walked all over Namtar's and that this is well maning experience talking not "lujo loves his binlor" or "lujo's unfamilliar with X" (I actually nicked the Binlor stuff from Avatar, originally I was avoiding it because it seemed cheezy and I didn't understand how Pissorf even works, and neither did he I think, he just res farmed it to death with everything. That got Binlor nerfed a few times when the devs figured it out, except we only scratched the surface with that when it comes to Namtar's Lair specifically).