you are 100% correct.
A XJ has no business on 35's if stock axles.
and a JK has no business on 39/40's on stock rubi axles.
For 35's XJ needs (yeah yeah I know you can do it with a dana 35 all stock) chromoly shafts, full case locker, and if abused maybe sleeved or trussed.
For 39/40's JKs MIN. Needs chromoly rear and rcv front axles, sleeved front housing and gussets on inner C's, and big brake kit. But should sell the rubi axles (they fetch about 2500-4000 pr) and invest in 11,000 in to real axles F/R.
But the point I was trying to make was that putting a 35" on a XJ is like putting a 40" on a JK. It fits and is common. Only the jk doesnt need more then maybe 4.5" of lift and complete axles to really do it right. A XJ needs Lots axle parts, Lots of trimming, and some form of cage, since it will be used for more extreme stuff after 35's im sure, and steering, brakes, etc. so its alot of work in either book.
But in a JK you can pick up the average woman and go out on a date, and then to her parents house for dinner with the family and then take them all out to the ball park for a game and home. In the typical XJ with 35's, you MIGHT BE EXTREMELY lucky and have a girl that will put up with the XJ, but highly doubt the rest of the night would go the same way. just sayin....