Clearcase was utter crap. 6 hour code checkouts and 2 weeks to setup a new developer is a freaking joke. I literally did a conversion from Clearcase to git and reduced the setup time to 15 minutes and this is for a code base older than Clearcase is.
Not to mention the absolutely bad design for handling merge conflicts (punt to human if more than 1 person touched a file seriously???)
If you're talking about Clearcase snapshot views, I agree they were garbage. And IIRC merging in a Clearcase snapshot view was also a hot mess. Snapshot views was a bold-on that we were forced to use in later years. TBH the migration to other VCSs was already underway by then in our company but snapshot views was the last straw for us.
On the other hand Clearcase dynamic views were pretty awesome. You just needed to edit your view config spec and the view FS would render the right file versions immediately. No checkout required. There was even view extended naming to let you open multiple versions of the same file directly from any editor.
As for merging Clearcase set the gold standard for three-way automatic merges and conflict resolution that wasn't matched until git came along. It's still superior in one important way - Clearcase had versioned directories as well as files so you could commit a file move and someone else's changes to the same "element" in the original file location would be merged correctly after the move. No heuristics, just versioned elements with versioned directory tree entries. Backporting fixes was a breeze, even with a significant refactor in between.
Git more or less wins hands down today because it is fast, distributed and works on change sets. But something with git's storage model, a multi version file system and Clearcase's directory versioning would be an awesome VCS.
Not to mention the absolutely bad design for handling merge conflicts (punt to human if more than 1 person touched a file seriously???)