Some people (I'd guess introverts, although I'm not sure) need to internalize to think and can't interact much at this point. Some can think and discuss at the same time.
From these two sets of people, some can afterward verbally explain the reasoning and the solution, some can't. Some may also only require a context warm-up.
That makes 4 sets of people already.
"Technical" phone interviews that screen candidates that can solve whatever riddle, filter for a very specific set of people. Not necessarily the best in any context. But a specific set that works for them. Just admit/accept it.
Having a few members who can solve hard problems on their own is great, and they usually have to be silent and focused while doing it. You also need people who are good at participating and helping and explaining their thought process. A team that has only one type isn't going to be the most effective team.
I've worked with the strong, silent type of coworker who has a solution in their head. But because they don't vocalize what they're thinking, I can't participate or help. That's not what I'm looking for in a good engineer and a good coworker.