I'm pretty sure that there'll eventually be some sort of LSD/locking programming for electric motors. Take the existing F-150 Tremor for example. It comes with a locking rear diff and a Torsen diff in the front axle. If you have a quad motor vehicle, someone could easily write a "locking rear diff" mode that simply has the rear motors turn at the same pace, and then have a "Torsen diff" mode for the front that will modulate the front motors just like a Torsen diff would.
You can see a quad motor Rivian performing worse than the new dual motor due this issue, the dual motor can use brake locking to send full torque from one side to the other, the quad motor cannot:
Electric motors have a lot of torque but EV drive trains are usually single speed so it must not have too much gear reduction for highway speed. A modern ICE offroad vehicle has a multispeed transmission with torque converter that greatly amplifies stall torque along with a transfer case that has a low range that multiplies even further. I would imagine when jeep does an electric production Wrangler it will probably have dual motors with lockers and may even have a 2 speed transmission for low range. Maybe they will even do like their Magento prototype and run a single large electric motor through a traditional transfer case and driveline.
The Rivian can do 908 lb-ft of torque. Like you say, that's divided up amongst the 4 wheels, so that's 227 lb-ft per wheel.
The Jeep can do 260 lb-ft total.
The Rivian weighs ~7200 lbs and the Jeep weighs ~5300 lbs.
So, with only one wheel of traction you're right. If you can transfer all of that torque on the jeep with less than ~14% loss (which, I dunno, might be reasonable) then the Jeep has more "oomph".
With two wheels, the Jeep is still figuring out how to distribute 260 lb-ft and the Rivian has 454. It's not close at that point.
Now have two wheels lose traction and you cut that down to 5720.4 lbs/ft at the wheels while a Jeep with lockers put the full 20k+ torque to any one wheel as needed.
Interesting thing about the Rivian quad motor version is while it has full software control due to a motor per wheel, this can be a downside for crawling like this because it has no way to send torque from one side to the other, so if say only two wheels have traction its torque is cut in half and can actually struggle to move forward as its also a fixed gear ratio.
Contrast this with say a Jeep wrangler that can have a locking transfer case with low range and locking diffs can send a lot of torque to a single wheel through torque multiplication in both the transmission and transfer case and everything locked up. Jeeps also have a decent brake lock diff even if you don't have lockers.