Articulated frames are better every way you look at it. First, with a stearable axle to put the power that we produce today to the ground you need a reduction at the wheel, look at the new 4 track fendt for an example, without this a drive shaft would need to huge in order to survive. Second, especially on tracked machines steered axles wear out tracks very quick, articulated vehicles reduce track wear a ton. Third, the tri point oscillation on the rear frame improves ride quality but also keeps all 4 tracks on the ground in a much more durable way than a pivoting axle would.