I noticed that many people post HUGE pictures that mess up the whole page. If they enclose these in spoilers, the page will be normal, until we click “show.”
If you don’t know what a spoiler tag is, it’s a bbcode that hides text (or images) from view until a button is clicked.
I think it might just be better to auto-resize attachment images. The forum already resizes linked images within the text, but spoiler tags wouldn’t work for attachments and I think most would forget to use them anyway.