The search and the interface are entirely the fault of MS as are the lack of more subtle features such as mass emails (which I have to use often while teaching online).
Mass emails via distribution lists are a thing - https://www.wisestamp.com/blog/managing-distribution-lists-i...
As is sharing links to OneDrive content with a password on it: https://support.microsoft.com/en-us/office/share-onedrive-fi... ("Set password: lets you set a password to access the file. When a user clicks the link, they will be prompted to enter a password before they can access the file. You'll need to provide this password separately to anyone you want to share the file with.")
(Poor quality sluggish Outlook client, dropping important emails into Spam, not being as configurable as a custom mailserver, hit-or-miss search results, those are all things I can agree with, I'm not just defending it).