This argument holds no weight as challenge by definition is:
(Merriam-Webster)
- to arouse or stimulate especially by presenting with difficulties
The risk and consequences of dying in XI is the difficulty by which players were presented a challenging WIN/LOSE scenario by which through whatever means necessary: you didn't want to die and desired victory. So yes having something to lose is stimulating and therefore challenging.
Difficulty by definition is:
(Merriam-Webster)
- something difficult: impediment
Dying in any game (and its consequences) impedes progress towards a winning scenario. The impediment of dying with a penalty certainly did raise the level of difficulty in scenarios that would otherwise take no thinking before action. That is why an R1 mob outside of a city isn't hard or challenging in comparison to a boss fight to end an entire expansion/mission line. In the same sense that fights got easier in XI when exp loss in certain instances was removed. At that point you could try just about anything without real thought or strategy to win and it wouldn't matter how many times it didn't work, as long as one attempt did.
It is hard to argue either way that all novices benefit from learning curves and death penalties. What cannot be denied is that having consequences in place will certainly help players realize their mistakes and attempt to correct them. Even as basic as dodging aggro or pulling too much enmity. A childhood 'timeout' of 150 seconds weakened alone can never achieve a true WIN/LOSE scenario, instead it's WIN/WIN which gives me no satisfaction. Think candy from a baby...