ClearCase is the worst VCS software that I ever used in my life. Maybe in the beginning of 90s it was better than existing alternatives, but I was using it well in 2000s, and it was horrible experience compared to already existing Git, Mercurial and even Subversion.

And if you add the cost (around $5000 per workplace), it becomes even less understandable.

It also required a designated CC admin or several admins.

I'm personally no fan of ClearCase myself, it's far to rigid for my taste.

But if I were the pilot in an F-22 or the Space Shuttle, I probably would want it to be even more rigid :-)

It's important to keep in mind the context of this machine and the software it was used to develop.