If by the numbers I can't murder your starting PC with a single lousy orc-stab, I don't want to play. It's that effing simple for me.There's a certain grimace to this attitude, one that very easily leads to cries of GM/Player entitlement depending on which side of the table you find yourself on. That's one of my least favorite conversations to have, honestly. The game doesn't happen without both, and driving a wedge between the two is the quickest way to ruin a group.
I want to refocus the discussion by asking a simple question: is character death interesting?
With few exceptions, I find the answer to be an unequivocal no. Before we get into arguments about DMs coddling their players or verisimilitude, bear with me. Character death is not interesting because it stops the game. No matter what your position is, I think we can all agree that playing is far more interesting than not playing.
At the same time, there needs to be risks of and consequences for failure. If death is the least interesting and least desirable form of failure, what are the other options?
The easiest, most common alternative to death is to take the party hostage. This creates a lot of great opportunity for roleplaying and building character motivation. If and when your players escape, they will want to get revenge after they've been tortured or maimed. The trick is to make the reasons why they've been taken prisoner specific to their captors. Cultists have something very different in mind than Goblins, as do the ranking officers of the neighboring kingdom who believe you have valuable information.
The least rewarding alternative is to have a band of NPCs conveniently swoop in and save the day, At its worst, it's going to look exactly like that: convenience. The important questions to answer in this situation are: why did the NPCs lend a helping hand and what did they expect to gain by doing so? This kind of help should never be free. At the same time, the cost has to be something the PCs can obviously provide.
This whole discussion is framed within a larger debate of power creep. I agree with Jeff that many modern systems start players off with far too much in the way of resources. The lowest levels of the game should feel destitute and dangerous. What I can't do is join the chorus lamenting the days when many a game were ended by the hooked blades of the Orcs. There are just more interesting ways to handle failure than tearing your player's character sheets in half and making them start anew, ad infinitum.