Not necessarily. Try this experiment:
In a correctly executed straight bar deadlift, the bar follows a plumb vertical path up to lockout and back down to the platform. The same is true for a correctly executed trap bar deadlift: the bar follows a plumb vertical path.
- Set up for a straight bar deadlift.
- Release your grip and have an assistant roll the barbell forward and away. Strictly maintain your setup position: knee angle, hip angle, back angle.
- Now rotate your hands from the pronated position to a neutral position
- You are now set up for a trap bar deadlift. Except for the neutral grip, everything else is precisely the same as your setup for the straight bar deadlift.
The point is that using a trap bar, you can set up and execute a deadlift exactly as you would with a straight bar. The only difference is the neutral grip, which for most lifters is an advantage from the standpoint of grip. Granted, with a trap bar you can modify the lift so it is a cross between a squat and deadlift. But nothing about a trap bar necessitates this.
Another objection that some make is that at the top of the lift, a trap bar is liable to swing link a pendulum, because it isn't braced against the front of your thighs. But if that happens, it is because the lift wasn't properly executed. In a correctly executed deadlift, the bar follows a plumb vertical path from floor to lockout. In a plumb vertical path, there are no horizontal forces to cause the bar to swing. (I would argue that because the trap bar can swing at the lockout position, it requires you to be more attentive to form and balance than with a straight bar deadlift. If you don't get that vertical path right, the bar might sway at lockout.)