I have done and it just posts the link and not the direct picture. But I've also been testing my iPhone the Using the desktop version of RWI instead of using tapatalk RWI. The result was I can upload photos straight from my iPhone library which you can't do through tapatalk. Result = no image hosting site needed as long as I stick with desktop version on my iPhone 7.
OK, here is how I stumbled upon:
Go to imgur iphone app
In your imgur album, tap the pic you want to post
When single pic comes up (5 icons on the bottom, heart on the top) - tap one more time - only one icon is left at the bottom (box with an arrow pointing up) - tap that icon on the bottom
Menu pops up - select copy link (very left side)
Go to RWI - you'll see 4 icons on the top (camera, pic, safety pin, 2 brackets with a line in the middle - click that one (very right side)
If select URL, it will only show the link - therefore, select IMG - then the pic will embed. Paste the copied link in between the two IMG's.
Hope that helps