I meant to write a blog post titled "What's good about ClearCase" in 2014, and I wish I did because now I've forgotten most of it.
ClearCase is a terrible version control system I wouldn't wish on my worst enemy, but it did have some good points that git still doesn't have. Large binary file support, configuration records, winkin, views.
With various big companies going towards giant monorepos and the local git repo just being a view into the super-centralized repo, I think they will re-invent parts of ClearCase.
Ah, ClearCase! The biggest pain was in your wallet! I saw the prices my company paid per-seat for that privilege -- yikes!