Say a 4.0 on a 3.75" (2.5" sl+1.25 bl) lift, highline mod, on 35" with super 35, lunchbox locker front and arb back. Will that take me on over the Rubicon and make it enjoyable?
My first trip over the Rubicon Trail was with a 2" lift on 32" AT tires, 3.54 gears, limited slip no locker. It was an epic trip, but not without rock rash and some "upgrade opportunities." Challenging? Yes. Enjoyable? Absolutely.
My second Rubicon trip was with 33" AT tires and rear locker, same 2" suspension lift but with a 1" body lift. Less rock rash this time, and the locker made more obstacles doable on the first try rather than the second or third. Still challenging, but fewer bypasses taken. Enjoyable? You bet.
My most recent trip over the Rubicon was with 35's and 4.56 gears, lockers front and rear, 4" suspension lift + 1" body lift, complete armor underneath. No bypasses taken. I had a great time on that trip as well.
I think you see the trend. A jeep "build" is usually an ongoing evolution taking into consideration the type of terrain one needs to traverse, geography, favorite activities, driver experience, skill level, budget, etc. A "capable" rig can be many different things to many different people and will change over time.
Don't worry about building the "perfect" jeep right out the box. Enjoy the journey.