We've found that our repos get bad branches and bad merges far less often with them. For a long time, we had issues where a repo would have to be completely rebuilt (or replaced with all history lost) after a dev who thought he knew the Git CLI did a merge incorrectly or force pushed something. Detached HEAD branches locally and remotely, incompatible remote branches, inability to merge without conflict, etc. It was always strange issues that usually required we branch off a commit on develop from a few weeks earlier, merge a few weeks of changes in a single commit, drop every single remote branch, and push and merge back into develop. Was a mighty pain.

We noticed that this only ever happened with devs who (incorrectly) believed they knew the Git CLI and as a result, we instituted a GUI-only policy and preinstalled SourceTree on all computers. In the 2 or 3 years since we started the policy, we haven't had this issue even once. We occasionally have a complaint from a new hire, but after a week or so, they usually tell us that they prefer using a GUI after all. I wish we didn't have the policy, but it became necessary, unfortunately.

(for reference, we are a small-ish shop. Never had more than 15 devs at once. That makes such a policy more easily enforced and worked around. We're currently reevaluating using SourceTree as the default recommendation and Fork is one of the options we are considering)