I can't find older posts (I bad at tags!) where I've noted the lack of D&D having any lose condition except for character death or total party kill.

So I'm surprised today to find a couple of people pointing it out on the wizards 5E playtest forum! Okay, massive post, but I'll quote the relavant bit.

Now he also have another point, that without some things a TPK is the only way to lose in recent editions.

 Exactly - the person refered to wants characters who go neg HP to stay down instead of popping back up from heals. Thus its a kind of 'losing' that doesn't involve the character actually dying.

It's one method of trying to put in losing without PC death - not the only method. It's interesting to see the 'you can't lose without a TPK/PC death' being stated by others as well.

50% wins, 50% loses = hamster wheel?

Tobold's been talking about having a 50/50 win/lose ratio in world of tanks, derived from the skill matching system.

He says it means your choices really matter on the field.

But think about it - overall, he's at fifty fifty.

You could flip a coin and get the same set of results!

Indeed a perfectly balanced skill ranking system just makes your skill absolutely moot! Flip a coin - same result in the end!!

However, I don't know if world of tanks has skill tiers like quake live does. Quake live has four tiers, so basically you can move up them if you do happen to make the right moves towards winning consistantly. So in those terms I'd pay that your choices matter.

But by itself - a perfect 50/50 is, just by itself, a complete waste of time in terms of gaming. It's just a hamster wheel.