I get the impression a big part is also just engagement, in a sense - social media is built to provide a constant stream of engaging content, keeping you hooked and anticipating the next thing.
Slowing down and doing something that isn’t so endlessly exciting might help, like watching a bit of a documentary, or reading a book (one that doesn’t however captivate you too much) seems like a decent idea, much better than doomscrolling or watching short form videos one after another.
I don’t think the reasons you stated are about bandwidth, and considering writing an email is IMO more effort than explaining on a phone call and will take me longer, I’d argue phone calls are higher bandwidth than email - at least in one on one conversations, since things change when you want to inform multiple people.
Though of course what you listed is important, and it sucks when people refuse to write out basic details that you could come back to later or forward to somebody else.