Cue swapping of personal email addresses... Most people can't be available on their phone all the time, meetings etc. A large part of email's popularity is that

Cue swapping of personal email addresses... Most people can't be available on their phone all the time, meetings etc. A large part of email's popularity is that you can communicate with people without having to both be available at the same time. The only other option is to leave lots of voicemails and that's way more inefficient than email.