Sure there is. Of course people want to use third party email or chat clients. In fact, this is in many ways the bete noir of Hacker News whenever a related sub

Sure there is. Of course people want to use third party email or chat clients. In fact, this is in many ways the bete noir of Hacker News whenever a related subject comes up, just today Slack blocking Iranian user. People point out that Slack, and Google Talk, used to have to speak Jabber. So I type my password into a Jabber WebClient, and I have just shared all the messages you sent me with a third party. It is literally this thing. People who used the Nylas N1 client, or now, any app that uses the Nylas APIs are sharing all their email messages, contacts and calendars with a third party - this includes your messages and your telephone number.