Long boring story as to why, but I had to do a lot of brake steering on the tractor I first learned to operate. Could steer it with the brakes about as well as I could with the steering wheel (going forward). Wouldn’t have a tractor I couldn’t brake steer.
If you have good traction on the front wheels, brake steering is useless. For example, if you’re running on dry ground with a bucket full of dirt in the loader and brake one rear wheel while still applying power to go forward, all you accomplished is putting all sorts of weird forces on a bunch of components from the front to back of the tractor without making an iota of difference in the direction you’re going. Not good.
It is sometimes useful when you don’t have good traction on the front wheels. I use it much less with the 4WD Kubota than with the 2WD Ford I learned on 50 years ago. Most of the time, even in slick conditions, with 4WD engaged the front wheels will pull through the turn without help from brakes.
So when is it useful? Examples I’ve had with the Kubota…
Mowing in 2WD to avoid tearing up the ground. Loader off. No front weights. One side in the bottom of a ditch mowing ditch bank. Trying to turn out of the ditch but the tractor keeps going straight like it’s on a rail. A little pressure on the uphill brake (not a lock up, just a little encouragement to turn) gets the front end turning out of the ditch. This is every time I bush hog the ditch by the public road, so it’s not a surprise. And yes, with that setup, I could lock a rear wheel and spin it on a dime, but that would also dig a little bare spot where the stationary wheel is, so not ideal for mowing.
Skidding a log in 4WD in black mud I could barely walk through. Grapple on front with another log in it so still plenty of weight on front. Turn right; go to the wood lot. Go straight; run over a 5’ bank into a creek. Turn wheels right. Still going straight, but now front wheels are plowing mud as they get shoved sideways. Tap right brake, tractor turns right, continue to wood lot. Initiation of problem to solution 2 seconds or less. Brakes were already unlocked because I knew I was skidding a log through a mud pit (it was solid about 8” down but snot slick until then).
Tractor getting stuck. One rear spinning while the other isn’t turning. Stab the brake for the spinning wheel a few times will often get you going again. Haven’t had much use for that on the Kubota with its 4WD and diff lock. Ford didn’t have either.
Last thing: brake steering is a LOW SPEED activity. If you’re in high range, lock the brakes together. When you first start, restricting to low range is probably a good idea. Depending on what you do with your tractor you may never have a use for brake steering.