Comparison, user custom sizing vs standard markdown + options/variations.
Re: https://meta.stackexchange.com/questions/388183/allow-pasting-images-in-html-format

Using img src @700px

Additional disadvantage here is that there's no click-through to full size, even though all the image data must be downloaded to view in-line.

All these have clickthrough to the full image. More important for larger images, detailed photos etc.
Using standard markdown

Using imgur's built-in data save resizing on a fresh upload of the previous image to save cross-referencing
Admittedly, this is even more effort than img src
Size l

Size m

Image pre-resized to 700 & saved as 50% jpg