The title is so misleading as Microsoft Stream has been part of M365 for ages. If you can recall, prior to this it was Office 365 Videos. It was a big deal then to move from Office 365 videos to Stream.
So what’s primarily happening now looks like the videos in Stream are now stored in SharePoint or OneDrive. So Microsoft needs to make sure companies get those storage dedicated for Stream (given below) to SharePoint.
"Microsoft Stream includes a base amount of storage.
A Microsoft Stream tenant receives a fixed allocation of 500 GB of storage and an additional 0.5 GB of storage per licensed user*”
Also, moving video files, especially the meeting recordings, to OneDrive was not a smarter move as OneDrive is a personal storage for users and when users leave company those OneDrives get deleted in 30 days by default.