I never s
aid it increases friction, and tyres are not linear, so actually having less loading is exactly what you want in some cases, to get more out of them for longer (the exact "maximum" load depends on the tyre's design point, and what direction it's applied in).
What it does do is increase the useful lifespan of a set of tyres, and reduces the bias between sides of a car in corners, meaning you can push both tyres closer to maximum load rather than being limited (in terms of acceleration, i.e. cornering speed) by the outside tyre's (designed) maximum load.
I don't see the point in arguing a difference of degree on this issue when it obviously works in real life (racing cars are practically always up against the regulation limit in terms of track width). And increasing the tyre size, using your linear tyres, "should" make no difference either - see
here. Obviously reality is subtly different from any simplified rule of thumb or superficial physical analysis.
Sort of, anti-roll bars are flawed as roll-control devices in that they attempt to pull up the inside wheel on its travel, effectively reducing the ride height on that side, giving the car a kind-of lop-sided stance, and physically moving the CoG lower - it takes effort to do this, too, which is effort that could be going into cornering (although it is likely a small drain that is largely returned on relaxation, depending on dampers).
Increasing your track width reduces the moment that causes the roll in the first place, meaning you need less anti-roll bar to start with. And it even says in GT's tuning help that anti-roll bars are not to be used to prevent roll, that's the springs' job! They're better for fine-tuning, especially for balancing front and rear "grip".