We are still considering this feature for future releases, and will continue to update the status when it changes.
Performance has been and continues to be a big focus area for Teams. One main area we have made improvements in is responsiveness for the most frequent user actions of switching between Chat, Channel, and Activity. We are also focused on reducing resource consumption and application load time. More improvements are on the way.
169 votes31 comments · Public » Apps, Connectors, Messaging Extensions · Flag idea as inappropriate… · Admin →
The feature team has declined this request due to the fact that a similar experience already exists.
You can achieve very similar functionality with the existing integration. The OneNote integration has been redesigned so that you can add an entire notebook as a channel tab, but always show a particular section (be it new or existing). Within each tab, you can also create other sections as well as pages within any section to better organize your notes.
Thank you for your feedback and suggestions.
I also dislike Teams creating a flat structure of sections per-channel in the root of the notebook, which creates a lot of clutter. However, moving the Team OneNote sections into a Section Group breaks functionality in Teams.