Re: They'd still be using...
My Mother had both her knees replaced in her 80's. She lived until just shy of her 96th birthday in her own home. IF she hadn't had them done she'd have spent up to 15 years longer in a care home.
The Economic case for her knee replacements is pretty clear don't you think?
Mum got her message from the Queen last month and still gets around the care home on her own. Perhaps in your ideal world she'd have been knocked off by the state years ago.
Pah, Bah Humbug.