I cannot speak for other devices other than a Mac or PC, which are all I use.
As for this happening only with large size pictures, that's not true. I've had to rotate images smaller than 1MB here and I've seen images larger than 5MB oriented correctly.
For me, it's an aesthetics issue. If your photos are turned on their side, even though when downloaded they will orient correctly, it still makes the original post look sloppy, which makes the site look like it's frequented by members who don't care what their posts look like.
I learned how to rotate my pictures several years ago through trial and error after I saw some of my posts looked like shit. Here is what I do:
https://forum.oneclickchicks.com/sho...d.php?t=229044
I'm sure if you Google the problem for other devices, someone in the ether has the answer.