We all have to make compromises in life. I think that is an easy one
Agreed if just posting a picture for appreciation. Basically there will be nothing to look at except the beauty of the scene, the composition, the brightness control or even the editing skill.
The issue would be on technical question, which I suppose could be the most useful place for a gear related forum to exist.
Whenever a question would be asked, e.g. why my shot is soft, why my output is dark, too wash, too noisy, burry... On DPR, the first recommendation would be "Please post a sample with full EXIF". From the sample image, we might guess where the problem would be and offer appropriate suggestion... Very often people might leave with happy result. As I was one of those happy beginners, I stayed there since then to learn and to help. If we would be limited to a small image, a lot of the original imperfectness would be hidden up. It would be hard to make meaningful judgement. Therefore whenever I would be on my phone, I would give a like to a beautiful looking image, but shall never offer any opinion on its technical aspect.
I wonder if this forum would be just a place for people who have interest in this hobby to hang around, to share their works, to explain why their owned gear great... it might eventually developed into a small community instead of attracting new comers, who normally look for answer of their questions and by a chance find and stop by this loving forum. If they can get nothing they won't stay long.
Could a similar approach of DPR be considered? When posting an image the embedded image would be compressed to a small size as it is now. But a link would be provided which allows interesting members to download the image in its original uploading size (of course, a limitation like not exceed 20Mb per image etc). This might not affect the brand width of normal forum activity but can allow members to download the full size image to examine the image when needed. My point is without a chance to examine the detail, it could cripple the good purpose of a gear related forum.
I noticed that this might be classified pixel peeking by some. But if we want to examine the technical aspect of a sample image it is the only way we can do.
My 2 cents.