I think both extremes are problematic; while you (rightly) cover the cliquey/othering/representation side, the counter is the introduction of people to the team who - at best - cannot or will not socially integrate, and at worst are positively frictional and demoralizing.

You see this happen a lot when (say) poor management look too much at cost or box-ticking over team morale and competence.

"Can they do the job?" and "can we get on with them?" are both important questions for a healthy team, but yes, it is important that those questions are asked in an open-minded spirit.