Why does the spoken word sometimes make us cry?

Today’s Zoom meeting (29th August) was extraordinary. Seven writers came together, some with last week’s brief of writing about family, one regular to listen in and critique, and newbie Harold. It turned into a very emotional gathering.
One of our fiction writers, let’s call him X, read his short story set in the trenches of WWI. It was about brotherly love and family tragedy and in reading it aloud, possibly for the first time, the author had tears in his eyes. It was incredibly moving.
One of our budding poets, let’s call him Y, was working on two poems, one for each of his teenage daughters and part of a legacy project. Towards the last line of the second poem he too was overcome with emotion and left the room for a short time.
Another writer, let’s call her Z, was in tears listening to those two poems and recalling her wonderful relationship with her late father.
There was a poem about a much-loved nephew, and a prose-poem for a super-hero mum.  There was also a poem about never met half-siblings and cross-siblings, due to the secrecy of emotionally dysfunctional parents. Or maybe they were just ‘of their time’.
So why can we write about emotional issues, and read them in our head, then end up in tears when we read them aloud? Of course there are scientific explanations as to why we cry, but saying something aloud perhaps makes it more ‘real’. Being moved emotionally has been described ‘as the sudden feeling of oneness with a person or other entity’. Being empathetic towards fictional characters, memory triggers, or simply writing and speaking about someone we have loved can have this effect.    
Today as ever, there was lots of positive but honest critique, but for those who feel that artistic creativity is surplus to human requirements (look at certain politicians as examples) I would say that creativity is one of the things that make us human; able to mine our own emotions and relate to others. It is cathartic, an outlet, a journey and a gift we give to others.