The thread is about bird species being pushed towards extinction because of housecats who are allowed to roam, not about the welfare of cats. "Cats can catch only the birds which come close to the ground to feed, or nest. There are precious few bird species in urban areas which do that."
What nonsense! Do some research.
I actually did a fair bit of research, for a university paper, into claims such as those of the OP in this thread. As you have apparently done research, as well, please share your findings with us? Which bird species are being pushed to extiction by housecats? I'm interested in hearing about any data you have.