I guess you don't have any grandparents who live alone, but can no longer reliably identify their own children....You are so deep into denial about the reality of aging
The "reality of aging" does include old people completely destroyed by aging. And we need to get serious about dealing with that, letting people check out when their life ain't no more fun.
But that reality also includes 90-something karate masters who are still practicing.
The "functional limitations" of which the author speaks can, to some degree, be mitigated by lifestyle. So can the supposed "lack of creativity" -- the problem isn't aging, it's stale ideas. Learn something new. Change fields.
My maternal grandfather was still quite aware, oriented, and active in his church at 90. And the heart disease that ultimately did him in could quite likely have been partially prevented or reversed with better lifestyle habits. My paternal grandfather was a bit short of his 79th birthday when complications from coronary bypass surgery (again, largely preventable) did him in. He never really recovered, emotionally, from the loss of his wife (could have used better social support, more community connections), but he was in no way crippled or suffering from dementia in his final years.
So given the example of my grandparents, with good dietary and exercise habits, good social connections, and a little medical help I can hope to get into my 80s with my brains mostly intact. (If we don't completely fsck up the planet, and if we make a few medical breakthroughs, with a little luck I hope to see the dawn of the 22nd century -- I'll only have to reach 131 to do that.)
Of course, I could also get run over by a bus this afternoon, or diagnosed with some particularly nasty cancer next month. One never knows.