And why does the board/shareholders allow a CEO to continue into their position by just following everyone else?
I'm sure things are different at massive scales, but I run my own side business (photography). I watch the local market, and I have the attitude of "Whatever everyone else is doing, I want to do the opposite." and it's worked for me so far. The area doesn't need yet another "dark and moody" photographer with boring sepia edits, blurry photos with a film preset, and the same exact font and colors on the website as everyone else.
You don't become a pioneer in your industry by just cargo culting everyone else. It's low effort leadership and if I were on the board it certainly would not inspire my confidence in their ability to run a company. You're telling me not a single person at the table asked "Do we have these engineers' institutional knowledge documented somewhere before we fire them all??"