Because I also know people who've failed and got fired. Quite a lot of them, in fact. As in "they failed and subsequently got fired".
The fact that there's some sample of "failed and fired" AND "failed and not fired" - even if this was 80/20, one still has to conclude that there's more than just failure at play. Inconclusive evidence to say it's only failure involved..
My experience hasn't been 80/20, it's been more 10/90. My whole company has people failing and founding around the place, I've only seen two people fired:
1 who blamed anyone else but himself, and another who never asked for help and wanted to save face at any opportunity.
Failures are a part of life, if you are at a company that doesn't acknowledge that I suggest perhaps finding someplace else for your own good
People who get fired are the ones who never learn, and have a shitty attitude about failure.
I know which camp I'd rather be in.