Digital communication technology has come a long way. But I expect this community has particularly high expectations. Am I wrong? :-)
Number one is allowing good stuff to be lost in the stream.
I worked remotely for nearly two years where Slack was our main means of connection.
I've also worked extensively with my own remote employees, collaborators and customers using early IM systems and wikis.
You have to allow editing time - someone has to be responsible for curating the important stuff and pulling items out of the chat, or cleaning up wiki pages so they remain readable and it's easy to find the key points.
Loss of tone. Misreading.