The death by a thousand cuts is real. Where I work we use Slack for nearly everything, we pretty much only have email addresses to login to Slack and AWS.
I have definitely found with the diverse bunch of people that I work with, that some people are very articulate in writing and some are very articulate in verbal communication. My personal experience is that people with English as a second language (in general) prefer written communication (they also write the best docs too). While native English speakers tend to prefer verbal communication for its ease and because of their comfort with it.
One piece of advice from me to you is to be careful of relying on speech to text for two main reasons: 1. Consider proper nouns, the products or tools that your customers are building or using. An example, I say "emacs", Siri on my phone thinks that should be "IMAX". Another example is `grep`, Siri thinks that ought to be "grape". Perhaps users would be able to define their proper nouns for flowy.
2. Despite having fluent English that is understandable to the vast majority of people, speech to text systems really struggle to understand me because I do not speak in a flat American accent. Perhaps it's just me :shrug: