I see categories in OWA and Monarch and can link categories to messages. Maybe I do not understand the point you’re trying to make. If you want to submit feedback, there’s a way to do it and now is a good time because Microsoft is very sensitive to closing the gap for Monarch to make it a “must have” client. See https://support.microsoft.com/en-us/office/contact-support-and-provide-feedback-in-new-outlook-for-windows-4a4bcc80-c71e-4e44-97c1-d0e62452ef4a