That's not how I interpreted the article, but I may be missing something. I haven't used Inbox, but the description below indicates it's for advanced users, not somebody's Aunt Floe.
"In parallel, the Gmail team would begin working on a standalone product specifically designed from the ground up for advanced users who have to handle a firehose of incoming emails every day. And that’s how Inbox was born."
I like Inbox, but in my experience it is inferior to gmail for that particular use case. Gmail does a far better job of displaying a lot of information that I can scan quickly. Inbox treats you email like a todo list and expects you to deal with everything (that isn't automatically sorted out) individually.
I use Inbox for my personal email, but gave up on it for my work email.
"In parallel, the Gmail team would begin working on a standalone product specifically designed from the ground up for advanced users who have to handle a firehose of incoming emails every day. And that’s how Inbox was born."