Just to add, consumer outlook / live / hotmail also benefits from this since it is also using Exchange in backend.

Additionally EWS is atually deprecated and planned to be closed on 2026 October for at least commercial Exchange Online (M365 / Cloud) customers (unclear from that article if free Outlook accounts also will be affected) although as with all MS announcements it will probably be prolonged. Microsoft Graph API is the new hot thing, but it seems some EWS features are not yet available in Graph API based on comments.

Another thing that in a proper company setting that uses Exchange Online you must approve applications before they can be used to access data (Not just Exchange data, this is Entra ID formerly Azure AD feature) for both EWS (in the past it was different, but now Oauth must be used which requires approval) and Graph API so company administrator will have to approve Thunderbird which many will not allow.