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.