Also, carefully laying thoughts out in text for 40 minutes takes a lot less time than explaining it meaningfully to multiple people, probably more than once if it was important enough. Absolutely nothing wrong with that.
To me calls are more about efficiency, I prefer to have a call and talk through a complex issue for 15 min instead of needing 5+ back and forth emails over an afternoon to get everyone on the same page.
Yes, either that or "I haven't thought this through well enough that I can explain it in writing, so please let me fumble through an oral explanation and—in all likelihood—waste your time".
Or, "I'm dyslectic and would prefer to talk rather than write", which is fair enough, I think.