I don’t think removing permadeath helps, as long as we’re talking the narrow context of “sometimes the board hates you”.
Removing permadeath will more dramatically affect that initial 10% you expect before you see what the RNG cooked up for you. It’s not going to have a big impact on that 1% when the RNG decides your off-color is the only legal gem and skulls are the only thing that can cascade on an opponent’s turn. I mean, it probably halves it to 0.5%, but I think that’s just make you more angry when it happens.
Thing is there’s any number of small tweaks that would make this situation better overall. I think the game designery question is:
We could just as easily be in the opposite scenario, with this task on the order of difficulty of a level 12 Explore: the top endgamers would already have every faction maxed and would be yawning about how there’s nothing left for them to do.
Now you have something left to do, with enough RNG thrown in it’s “hard”. The devs did this to buy some time to make more things to distract you. I am extremely confident once some new Delve-like thing that’s just as ridiculous comes along, they’re going to dramatically decrease the difficulty of finishing Delves. A new map arrives in 5.0, I think? Perhaps that’s the thing they’re waiting on.