Yes, I didn't say that it's impossible, only much more difficult to achieve such kind of performance in a wheeled vehicle.
Fact itself that they need stabilized legs is a proof of it as many tracked ones didn't have them anymore.
I quess that's the trade off between cost/mobility - on desert or urbanized areas wheeled howitzers have better mobility and dont need lorries to move.
Now, if they are needed just to achieve 360° coverage it would be an excellent news.
I didnt frankly tracked howitzers firing 360 pics. But I guess support legs are just to absorb recoil and not pass it to truck suspension + stabilize center of gravity.