In my experience, the further up the org chart you are, the less likely you are to use Slack directly, instead deferring to assistants or at least only posting announcements periodically.

Ditto goes for Internal IT who I've commonly found never use these chat platforms instead deferring (correctly) to ticketing systems.

Those two groups are both the ones who would probably advocate for adopting these platforms yet they never use it in any regular sense so they don't feel the sharp edges