Most jobs don't require people who can endure getting "pushed to the limit" every week, hour, day, etc. Especially while under close observation and scrutiny. That would strain most any person. If it is that demanding, then be upfront about that instead of surprising candidates during a stressful interview.

People should be aware of what they accidentally select for in candidates. I feel like I am skilled at remaining calm in crisis work situations where people (customers, co-workers, owners) are dependent upon me, but I can bomb interviews just as easily as the next person. Some approaches might consistently filter people who get stressed during interviews, rather than select people who maintain poise.