I agree; I find the attitude surprisingly paranoid as well. And surprisingly protectionist and anti-collaborative.
The failure of collaboration was on the part of the DM in the example of the Lich. The DM took out a bottle of white-out and overwrote a significant part of the player's backstory by turning the mother into a Lich from nothing. The attitude that you can retroactively change someone else's input without consulting them is anti-collaborative. And is an active disincentive for the PCs to collaborate
because they know their work won't be respected - instead it will be twisted and the spirit changed for the DM to drop his railroad tracks onto.
Now, not changing the mother's character, but giving her debts etc. would be a different story. When collaborating, you build on the work of the previous person rather than completely change it. Or you ask them about major changes.
I also think that it's vitally important to not identify too much with your PCs. You are not your PCs. If bad things happen to your PCs, you, as the player, are part collaborative creator, but also part audience. The point of bad things happening to your character is to entertain you.
Clearly, if you aren't entertained by the specific bad things that are happening, the scriptwriter has failed.
The attitude of being really paranoid and protectionist about your PC seems unhealthy to me, and I would find it a crippling environment in which to run a game.
And the attitude in which the DM has the right to re-write any part of the background I submit, and tear up the spirit, has been crippling and disempowering and made me wonder why, if I wated to watch a pre-scripted story, I wasn't just watching the TV.
Well, of course the GM's going to try and screw your PC. As long as he doesn't screw over the players then, all's well.
And if the DM wants to screw my PC in dramatic ways, I'm probably going to help. I
always try to include some dramatic hooks or some motivations for the DM to entrap the PC in a backstory. And if the DM uses them, good! That's what they are there for. And that is what collaboration is about. If the DM instead chooses to drive a bulldozer straight through the backstory, demolishing the houses to lay down a railroad, then I might as well not bother to give the DM anything. He's going to set up his damn railroad whatever, and if I give him no reason to pick on my PC I won't have the history and motivation twisted in ways I don't understand.
Shorter me: Collaboration is good. But collaboration involves the DM respecting rather than overriding the player's choices in backstory as well as RP.