Why do you leap from I personally want hardship driven from mechanics (Great! Go wild!)
If there are no mechanics reinforcing it, then there is no hardship. If for example, there are no consequential mechanics for fatigue then a PC can always go on with any length of forced march. Yes, they could give some sop about how he's struggling through the pain and fatigue, but that would be at that point meaningless color, and more importantly it couldn't be enforced. The player could, absent fatigue mechanics, march on claiming his character is a fresh as a daisy after seven days march over 400 miles without sleep, food, or water.
So what do you mean by hardship not driven from mechanics? And how would that be meaningful if the player had no investment in it?
There can be no meaningful loss/consequences if it's not mechanically enforced (Lots of people in this thread disagree with that.)
Lots of people say a lot of things, but the fact that a lot of people say it doesn't mean it's true. There are no meaningful losses or consequences if there are no meaningful losses or consequences. I feel like that is so obvious I shouldn't have to say it, but here we are.
and from there to People who play differently than me are ruining the hobby?
People can and always have played differently than me. But hitherto, they never demanded that games conform to there preferences not only in the house rules but in the core rules. You know how hard it is to build consequences back into a game that removes them? Probably 75% or more of a game engine is defining consequences mechanically. You take that out and you've gutted your game. It's easy to ignore rules. If you want to ignore fatigue rules, you could. If you want to ignore lasting damage, it's easy to do that. You could probably manage that in a single house rule of a single sentense. But building back all the rules systems for exposure damage, or crippling injuries, or disease, or whatever is hard.
I strongly disagree that your conclusion inherently follows from that premise.
Ok.
This is simple. If there is no negative stake, then the story path never branches in a meaningful way. If the goal of the game is winning, but winning is the only outcome, then what's the point of playing? (Note, I'm not saying there wouldn't be a point in playing, I'm asking you to analyze what that goal is.) It's at this point that people invariably bring up story factors of some sort like, "You didn't get to rescue your sister." or "You didn't save the town." or "You didn't win the love of the handsome prince" or whatever. But my experience is that any player unwilling to risk his characters life utterly and completely doesn't care about the rest, because they are the sort of player who says, "If the stakes are my life or an NPC's, well then my life". And if they are that sort of player anyway, how does failing to save the sister bother them when they no longer have their character's life at stake? You can't suffer failure in a stake you have no investment in. When I told my player up front that if they went into the dream and they failed their dreaming skill check, they would be stuck in a permanent coma with no one who could get them out, and they did it anyway, then I knew they cared about the NPC. But if there was no chance of loss, then what is really at stake?