Because believe it or not, a chat/conference is the most easy gateway to an "everything app" just like with WeChat. Afterall, a chat/conference app is a microcosm of the "internet".

Your chat app is great but imagine if we can send/share audio clips too.

Your chat app is great but imagine if we can send/share video clips too.

Your chat app is great but imagine if we can send/share live video too.

Your chat app is great but imagine if we can send/share money too.

Your chat app is great but imagine if we can send/share conference meetings too.

Your chat app is great but imagine if we can send/share calendar invites too.

Your chat app is great but imagine if we can send/share food delivery requests too.

Your chat app is great but imagine if we can send/share gaming sessions too.

Your chat app is great but imagine if we can send/share X too.

There is no limit on X. The internet is about sharing X. a chat app is about sharing X. There is no bound to how much it can grow really.