You have different players, and a different dynamic, than I.
We agree that RPGs are a group activity; that's a start.

That said, hockey is also a group activity; where two teams are trying to win and in doing so will often push the rules envelope as far as they can until-unless the ref calls a penalty.
As a player at an RPG table, I see my main purposes being to roleplay my character in-game and advocate for my character out-of-game. Among other things, that out-of-game advocacy includes finding ways to make things easier on my character in the game...which in turn means pushing against the rules envelope if the opportunity arises.
It's the DM's job to push back, and make sure I and-or the other players don't break the game; and it's on me to accept that pushback if-when it comes.
I get this sentiment. My concern with defaulting to easier encounters is that doing so will set expectations among said new DM's new players that that's how it'll always be, leading to dissatisfaction and complaints when the difficulty gets ramped up later.
It comes back to the premise that "start hard then ease off" is a better formula than "start easy then (try to) add difficulty".
Here's the Bad Things breakdown, by adventure number. It seems I'd forgotten a few...
1. none
2. 1 level drain, 2 major agings (which I'd forgotten about in my previous posts)
3. 1 level drain, 2 limb losses
4. 2 deaths (1*), 1 perma-poly*
5. 1 death
6. 2 deaths
7. 3 deaths, 1 major item loss*
The ones indicated with '*' are either permanent or will require Something Very Big to undo e.g. a wish. The two deaths in adventure 4 were the same character; bad luck for her, and she declined revival the second time. The death in adventure 5 had nothing to do with the adventure itself; the party found unrelated trouble while travelling and it went wrong.
This run covers about fifteen real-world months of regular weekly play.
Fair enough; and it's not like this lot hasn't had (and still has!) story-based challenges as well. Adventures 5-6-7 above are the first bits of what I hope will be a 5 or 6-adventure arc (or mini-AP, if you like); and sooner or later it'll become clear to them that to complete it they're going to have to find a way to fix that "major item loss" noted above...