In my case because of the asynchronous nature of text versus vide or voice calls. An effective compromise is voice notes in modern messenger systems, which preserves asynchrony while also allowing the expressiveness of speech.
Voice notes, like email, are fully async and require actually listening to someone talk, which changes the communication media that you're working in.
Messaging has risen to the prevalence it has because of the features it brings to the table, not in spite of them.
- you send me a picture, it may be ambiguous;
- you leave me a voice call, I have to go out of the meeting room to listen to it
- you write a message, it just works. If there is info to use, I will easily copy your message in any application (Excel, Word, SAP...).
Also, text can be stored easily, so I will keep an archive of your text, probably far less an archive of your voice message or diagram, as they are very heavy.