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.

Idea for permanent death (in any game)

Killed by a grid bug!

Instead of only choosing your characters first name, you choose their surname, then their first name (or use the random option)

What happens is you have two records of your level - current level, and top level gained. Top level gained only goes up when your current level exceeds the top level.

When you die your back to first level! And the first name is gone - that guy is dead! Your 'character' is known by his surname, because your playing a family heritage, not one guy.

However, by paying money and using certain items (that can only be used X number of times per RL day), you can boost your level back up to your top level gained. The smaller the gap between current level and top level, the less you have to pay. Also paying only lasts for awhile, so although it's alot like most traditional mmorpg, it's not always that way and by default, if you don't have the money and items, your back at level one.

Indeed I think ages ago I heard of some game that used a family system along with perma death, but I can't remember it.