Need picture size posting guidance for this thread so I won't upset anyone. Did some searches but couldn't find anything definite, so....
I've never seen anyone complain about image sizes on this thread.
I'm sure some people post 4K images - I never look at them at full size if they do.
I personally don't care if full sized images are inserted directly into posts without spoilers because my browser sizes them to the proper width on my desktop (I run at 2560x1440). In fact I prefer that to just attaching a thumbnail that I need to click to view.
I guess large images would only be an issue for someone paying for data.