That's the whole problem with Teams, because they get to ride O365's coattails they don't really /try/. The fact it is better than Skype for Business is more an indictment of how bad S4B was, not an actual defense of Teams as a stand-alone product/app.
Let's look at the popular things they haven't done:
- Show video for all people in Video meeting: Created 2016. 37K votes. "In the backlog."
- Multi-window for chats and more: Created 2016. 17K votes. "Internal testing."
- Compact mode: Created 2016. 16K votes. "Not even in the backlog, we cannot figure it out" (in spite of multiple third party CSS hacks that accomplish it convincingly).
- Move a project (channel) from one team to another: Created 2016. 15K votes. "In the backlog."
But don't take my word for it, review what they have actually accomplished from their own UserVoice here:
https://microsoftteams.uservoice.com/forums/555103-public
But it is popular because it is free and bundled with something successful, so the Teams team can sit around for four years with little to show for it.
When will Teams actually be good when measured against the market rather than the [worse] thing it replaced?