Okay did we not have in prior versions the setting called inline images?
Which allowed any attachment smaller than the setting to appear without a url link but the full image.
That's from an internet time prior to mobile views and responsive design. That was based on the FILE SIZE of the image. UBB.threads can still manage the display of images based upon their file size
Control Panel > Attachments
The modern internet requires a need for reduced file sizes AND images that have their dimensions displayed within the confines of smaller (portable) screens. We now enable the web server graphics library to compress images as they are uploaded, reducing their file sizes, and lowering their image dimensions to a height/width maximum value. We also manage the display of images to fit within the user's mobile/tablet/laptop/desktop screen vs the older arbitrary way of giving the image a static width to fit just on a typical desktop-size screen.