All trailers can sway. The predominate factors are
1. Speed - which provides a source of energy that could translate into sway. Particularly under braking where excess momentum of the trailer tries to outrun the tow vehicle by translating into sway.
2. Loading - particularly not having a COG far enough ahead of the trailer axles for stability, and too much mass behind the trailer axles possibly amplifying resonate sway forces.
What makes travel trailers potentially more prone to sway are a couple other factors. Exacerbated with longer trailers. Just because a long trailer is within weight limits, there's still more danger.
3. Lateral aero push - with larger slab sides to catch wind, effectively tacking in the wind like a sailboat, adds to lateral side forces. The larger the sway event / angle of incidence, the larger the lateral force contribution. Particularly dangerous when combined with the next factor
4. Trailer yaw moment - having more yaw momentum that a towing vehicle has to manage or arrest upon a large sway event.
It's especially important for a tow vehicle to dampen and constrain any lateral movement to begin (cue WD hitch) with because sway forces can get further amplified once set up. Less compliance in the suspension, tires, can help and inflating tires incrementally more on both the tow vehicle and trailer can be a dial towards better stability.
The 200-series, while having a relatively shorter wheelbase, does have significant mass, especially mass at the rear axle (versus an unladen truck) to dampen sway forces.
Weight distribution hitches are a huge lever and factor to increased stability and margin of stability. There will always be incidentals on the road like unexpected gusts of wind, dynamic situations needing emergency braking or maneuvers, flat tires, failed trailer brakes, etc, that could make a once stable articulated rig, unstable.
It goes beyond that too. A WD hitch doesn't just create more stability. As its namesake, it also distributes weight back to the front axle. This helps the structure so all the tongue weight and dynamic loads aren't purely in cantilever on the ball. The rear axle and tires don't have to work as hard. Prevents unexpected understeer because the front axle doesn't have as much traction for positive control. Shortens braking distances.
And just because a vehicle can be made level via spring rate or airbags,
is no where close to the same thing.
IMO for even a small 22' travel trailer, there is no way I wouldn't run a WD hitch for that extra measure and margin of safety. From my experience with 20' to 28' travel trailers, the WD hitch always makes for a better handling and more stable rig. Better ride comfort with less porpoising.