That was my interpretation, too. One would think that after 17 years at a company like Google one wouldn't need to have "to prove" himself/herself anymore, crazy.
Unfortunately this is not an isolated case. I have seen it play out way too often with individual contributors (ICs).
I have been in enough promo committees to recognise a pattern.
You have an IC performing perfectly fine, year after year, producing high quality work. After 3rd or 4th year of them staying in a position some senior director raises the inevitable question; "why is this person not being put up for promotion?" which then leads to "why are they not growing".
The person in question is just not interested in growth-treadmill anymore but no, our system won't let them work peacefully. ICs have to either grow or move out. All the while the management layer who create train wreck after train wreck ("bureaucratic mistake" as the author charitably puts it) will seamlessly glide within and between companies.
ICs have to prove relentlessly whereas managers coast along.
Is that the case for seniors, though? I got the impression that once you do move up a bit, the expectation that you have to be growing forever kind of goes away.
