I have been a professional developer for 20 years, 10 of those remote. He is right. If people learn how to work and communicate through async text, you can come up with ideas, exchange thoughts quite easily. Problem is, most people love to hear themselves talk so dismiss ways where they aren't the 'center of attention'. I would say in 20 years, less than 5% of the 'meetings' or 'coffee chats' couldn't have been done through slack/irc/whatever.