They absolutely can
It’s worth noting that there are several obvious reasons that Force users rarely use the Force to snap their opponents necks in combat:
- First, using the Force in combat is difficult. It requires concentration, and much of the time, it’s hard to find an opening: i.e., enough to time to concentrate in order to use the Force against one’s opponents. We certainly do see people employing the Force against Force-sensitive opponents, but usually only when there’s a lull in the lightsaber combat, which supports this hypothesis.
- It’s not easy to do fine manipulations with the Force even outside of combat. Throwing one’s opponent across the room is easier than snapping their neck, which is easier than turning off their lightsaber, which is easier than pinching a nerve, and so forth.
Most important, what can be done with the Force can be blocked with the Force. We see several examples of Force telekinesis being blocked with Force telekinesis, including the famous scene where Anakin and Obi-Wan try to Force push each other.
We can reasonably assume that, during combat, Jedi and Sith are on guard for the most obvious and game-ending moves, such as using the Force to grab the other person’s lightsaber, turning off the other person’s lightsaber, snapping their neck, and so forth. When someone tries to use one of those moves, their opponent simply blocks it. So they generally don’t, unless they can find an opening. When Count Dooku throws Obi-Wan across the room in Revenge of the Sith, for example (already not particularly common), it’s probably because Obi-Wan is stopping Dooku from breaking his neck or stopping his heart.
When we do see such a move, it’s often evidence of how amateur one Force user is relative to the other. For example, it’s obviously possible to use the Force to snatch someone’s lightsaber away, as Vader demonstrates in Star Wars 2: Skywalker Strikes, Part II:
We’re clearly supposed to see this as evidence of just how little Luke knows about the Force at this point (this is right after Obi-Wan’s Force spirit has told him to run): he can’t even stop Vader from taking his lightsaber. Worth noting is that Vader doesn’t try this on him in, say, Return of the Jedi: presumably Luke has reached the point where he can at least keep his lightsaber in his hand. There are innumerable other examples of Force powers being used against the inexperienced, but not the powerful: Yoda freezing Asajj Ventress in place (The Clone Wars: “Ambush”), but not Darth Sidious (Revenge of the Sith); Darth Vader trying to make Ezra cut his head off with his lightsaber (Rebels: “The Siege of Lothal”), but not Ahsoka (Rebels: “Twilight of the Apprentice”)….
That’s why we more often see Force choke and similar techniques used as a punishment or so forth against non-Force-using characters: because the Force users can block it.
All that said, though, the Force can certainly be used to snap someone’s neck, as we see in Star Wars #2.
The Force can also be used to kill people in other interesting ways. For example, Vader used the Force to, most likely, crush the heart of a wayward Imperial prefect:
Vader came to an abrupt stop, scanning his audience and certainly
sending shivers of fear through everyone—Toydarian, Dug, and
Devaronian alike. As his raised right hand curled slowly into a fist,
many of them began nervously tugging at the collars of their tunics
and cloaks. But it was the Twi’lek prefect, standing not a meter from
the Dark Lord, who unexpectedly gasped and brought his hands to his
chest as if he had just taken a spear to the heart. Phoca Soot’s lekku
shot straight out from the sides of his head as if he were being
electrocuted, and he collapsed to his knees in obvious agony, his
breath caught in his throat and blood vessels in his head-tails
beginning to rupture. His eyes glazed over and his red skin began to
pale; then his arms flew back from his chest as if in an act of
desperate supplication, and he tipped backward, the left side of his
head slamming hard against the blood-slicked floor.
Vader crossed his thick arms across the illuminated indicators of the
chest plate. “A pity. Tasked with controlling crime in his sector, he
succumbed to temptation by hiring himself out to the Droid Gotra.”
“Well, clearly his heart wasn’t in it,” Tarkin said. “Strange, though,
that the Crymorah crime syndicate had no representation in your
Both the examples are against non-Force-users, adding yet more evidence that such techniques are generally ineffective against Force users, due to their ability to counter them.