Using Outlook for Android in business environments for email and scheduling
I contacted support. They said it's by design. I informed them that no other version of Outlook on desktop, Windows 10, the old Windows phone (which my Lumia 950 of 4 years just died) nor old Windows mobile. Then they came back with this response...
"You can however just put the pictures in a zip file. When you attach the zip. It will be considered as an attachment."
What an absolute stupid idea. People shouldn't use zips. People who don't know enough could open one then execute a virus inside.