When "interviewing for fit" or using a "gut check" method for selection...

You may be compromised with bias because you can have great rapport with someone, but it doesn't mean they can do the job.

You can determine things like speaking in public, confidence, eye contact, and other critical functions that will be always be important to their success with technical duties.

You can get to know them personally and determine how they will get along with the team or with you as the manager, which matters more than most other requirements.

You can get a good feel for how they align with you as a manager, your team, and the overall beleif system that will make them perform well.