Yes -- I would think laregely because GitLab include in their instances thus Mattermost is the devlopers/tech persons choice of chat app while Slack seems more

Yes -- I would think laregely because GitLab include in their instances thus Mattermost is the devlopers/tech persons choice of chat app while Slack seems more suited to general public and GSuite Hangouts will likely become the enterprise option due so many enterprises already paying Google for email services etc.