This is just far too simplistic to be “true”, although I grant that there could be an element of truth to it. From all that I’ve read and learned about it, there seems to be a confluence of factors that lead to stuttering. It’s one of the only types of “disabilities” (or whatever term you use) that seems to be intermittent, almost arbitrarily. I might be able to say my name fluently today...and then tomorrow I can’t even introduce myself. I can speak to one family member this minute, but if the conversation continues, at some point, without warning, I can’t speak three words in a row without severe blocks. If it were as simple as one factor...like blood flow or something else...I feel like it would be easy for medical professionals or scientists to isolate the problem and then “solve” it. I think physical, neurological, and psychological factors all play some kind of part in it. And the level of each individual factor can change, depending on age, circumstance, physical location, time of day, physical health, etc.