Our TT delivered from the dealer was 6900 lbs...I added a second battery, spare tire, jack, tools, heavier foam mattress, plus all the dishes/linens, BBQ etc etc etc. At the scale with "some" water in the fresh tank it weighed 8500 lbs. When we dry camp and I fill the fresh water all the way and bring the coolers and firewood we're closer to 9000 lbs.
Doesn't matter what's in the trailer, and packing light doesn't help stuff like a spare tire or generator....so the 1200 lb number is a rough way to estimate what the TT is likely to weigh in addition to the dry weight when all is packed and ready to camp.
Too many newbies shopping the dry weight of the trailer against the tow rating of their truck...then was proposed by many to shop the GVWR of the trailer vs your tow rating, but then you're assuming that the thing will be stuffed to the gills. Obviously no two campers pack the same stuff the same way, but the idea was to give folks a realistic estimate of what they will to the dry weight.
If you look at the responses to this thread you can see these numbers are pretty accurate. Of course smaller trailers that don't have much storage limit what you can pack by default.