Listen, there's a difference between challenge and "A fight you are not expecting that you absolutely cannot win unless you prepare ahead
Indeed ... but your previous words didnt include any challenge at all.

prepare ahead which you can't because in character you don't know it is coming.
Wich you totally can and totally should.

Maybe we play different kind of characters, but mine is usualy fully aware that this world is freaking dangerous ... therefore they leave the camp only if they feel like being preared for that danger.

I mean what preparation can you do anyway ...
Cast Mage Armor, and False Life or Armor of Agathys, summon your familiar, drink some resistance potion (I mean why would you drag them otherwise? Its too late when you are allready burning.

) check if each member of your party have enough potions and poisons in case you would meet any danger (Not important since we have Magic pockets tho, and can drink potions straight from someone else inventory

) and that you have right artefacts equipped ...
And thats it.

All seems to me like proper preparation before you go adventuring.
As for positioning before battle, wich is also kinda preparing ... Githyanki start to turning this tactics against me lately

...
But if we put aside the fact that this game is for some reason forcing your whole party to be present personaly no matter if they really stand next to your character, or hiding in the bush abowe trying REALLY hard to remain undetected ...
Then it also makes sense, you just withnessed them as they murdered to death bunch of Flaming Fist knights, just bcs ... Zoru (presuming you talked to him) told you they are cold heart murderers, and Lae'zel confrims this by mocking Zoru that they didnt cause his friends additional harm by twisting their blades ... any sensible party (by my opinion at least) would split into at least two groups, where one would go there and talk, and others will hide around and act as backup, in case something would go wrong.
Sure if you have all the perfect spells prepped and you prepare your party just so that that everything is just right and you've got through the underdark to pick up the adamantine armor then yes, sure, maybe you can win.
You exaggerated and you know it.

Come on, if you really want people to take this topic seriously, then try to take it seriously yourself first.
But not when you are level two and a character you have at least some reason to trust tells you you MUST go there only to die.
Nope ...
You die if you go there AND you start a fight ... but you certainly dont "must" go there ... and you also certainly dont "must die" when you go there.

Those statements are simply false.
That's not fun. That's not good gameplay, and y'know what? if that happened in a real TTRPG I'm betting all the players would walk away from the table.
Well, knowing my party we would certainly not.

We had some "they are too strong" encounters in the past ... NPCs were yelling at us that they will stall them and we should run ... exactly the LotR "run you fools" scene ... but we (to our DM discomfort) said "then we die fighting" ...
He learned tho, in next scenario he used infinite spawn and added 5 enemies each round, so we finaly understand he REALLY dont want us to fight here.

But it was fun. ^_^
But even if ... so what?
I mean it was their decision to ignore all the hints and red flags, it was their decision to start a fight or pick those lines that started it, it it all consequences of their own actions.
And sure, some snowflakes that were expecting railroading and plot armor from DM would certainly melt ... but sometimes that is for the best.