I’ve heard this “conclusion” from many people over my career. I disagree as a general rule as much of my work is scientific and technical and long replies are more useful than talking as having things written down makes things reproducible and shareable.
I think long emails are bad ways to deliberate or debate or to collaboratively create. But they are great for communicating complex ideas to variable size audiences (ie, one person forwards to their team or files things off for later reference). Even better when accompanied to a link to a web version that can be revised with additional info later.
This really helps due to the async nature. Getting on the phone with someone and talking through an idea with them assumes both parties have time to do that. And is a silly suggestion when 5 people need to read something.
I find it more efficient to get a thoughtfully crafted email than a phone call that still will need to be followed up with an email to confirm all parties understand.
My, probably wrong, take is that the “talk, don’t write” people is based on their inability to logically think through, structure, and communicate their ideas and, instead, would rather connect directly and hope the solution emerges from a conversation.