I've seen people leave with and without. As to why they've not left with dignity, it's sometimes not one-sided.
Edit: For those who are making many negative guesses and assumptions about my comments. My comment had nothing to do with the OP's personal life at all (as I know nothing about their personal experience). My comment was simply to make a counter-claim to the blanket statement that the church allows no one to leave with dignity.
The OP has since shared more details about their personal experience, which was absolutely a terrible experience in every way. It's awful that they, and their family, had to go through that. If I feel so awful about it, have I ever attempted to reduce the likelihood of such things happening? Yes! I have.
I have also seen people leave the church without any great undue process or negativity—or loss of dignity (in my interpretation of what was meant by dignity).
Edit [2]: There has already been more than 1 other person comment, who has left the church, who didn't experience any of the negative things that the OP did. That doesn't mean that OP is lying, exaggerating, or anything, it's simply my point—OP's experience is not the universal experience, nor the officially designed experience. Is OP's experience more common than it should? Absolutely yes.