The rules are still there and very much applicable. It's just that we can't go through every thread checking for rule violations. The change in forum limitations (lack thereof) does not mean the rule itself is lifted.
The reasons for the rule are few but quite relevant.
- Data limits. Larger images will eat into the monthly/weekly/etc bandwidth limits of the visitors to that particular thread. It may not bother me or anyone else with unlimited data. But let's assume i used my mobile phone to browse the forums, all mobile operators here will limit bandwidth after X number of gigabytes of data transferred. The screenshots section of the forum is nothing but images so it makes sense not to visit those with limited data transfer.
- Low bandwidth. It's going to take forever and ever and ever for people on slow connections to open a thread that's jam packed with huge images. Regardless of if it's screenshots or not.
- Forum layout on lesser resolutions. There are still users on 1024x768 displays out there. Be it on mobile phones, laptops or otherwise. Posting a large enough image or concocting a certain non-breaking string will break the forum layout in such a way that it becomes nearly impossible to read posts that are more than just "+1", "great shots and trucks" or "thenx foar teh mods". Even if MOST of us here have FullHD (1920x1080) resolution monitors, it doesn't mean you automatically gain the right to assume everyone else are fine.
- Loading time even on fast connections. If a thread has a lot of large images in it, it's going to change layout over and over again in any browser. The larger the images are, the longer it takes to load a particular page even on a gigabit internet connection. (the bottleneck is remote, not local)
- Finally, as always, the attachment function is ONLY to be used for bug reports and technical issues with the game itself. Still, if people upload larger images (such as 2k or 4k images) to the forum itself, the forum will finally succumb to bandwidth and processing power limitations. Ruining the day for everyone here.
Even though all those points are valid for all users, sometimes (at moderator discretion) it's OK to upload larger images. Personally (even acting as a moderator) i don't give a hoot if you share images in 1280x1024 or even FullHD in the screenshots section. But be mindful of everyone else visiting said thread.
Either way, it's actually quite trivial from SCS's side of things to make images 960 px in size even though they are larger originally. It still wouldn't solve points 1, 2, 4 or 5 though.
On extended hiatus.