I'm not saying you're wrong, but in my experience few are thinking just about their CV or promotions, and most product changes are driven (at least publicly, within the company) by a desire to improve offerings for users.
The key is: "publicly, within the company"
"We need to spend some time fixing technical debt for the last product feature we rushed to market, as it generates too many support tickets."
versus
"We delivered dark mode. Shiny!"
This was a product that was meant to drive some KPI metric of some large organization, and it was launched with the full intention to drive it for years. Then when it wasn't meeting some target, instead of steering the ship in the right direction, the directors or VPs who funded the effort likely got bored and moved on to the next KPI.
I'm sure a lot of folks at the bottom worked very hard on it and were proud of it and definitely deserved the praise on their performance reviews. However, once it lost its director or VP support, there would have been no way to keep it running.
If you have no insight on Google internals, you really have nothing to reply to my question (as other's responses to your comment show).