He did wipe out the order though. Sure he didn't kill all of the Jedi but the teachings any survivors could give out are suddenly fragmented, and it's not like any of them can meet each other without risk of getting gunned down by Imperials or cut down by Vader himself. While other Jedi locations exist, Anakin took the home base. Anakin marched on the temple leading the 501rst to kill everyone inside and as we know now, the Jedi temple was converted into a palace losing a lot of the Jedi knowledge along with it.
Not to mention that Luke later on only had two old guys with incomplete teachings to give him so it's not like Luke had a vast archive to go through. There's probably a good reason it took 30 odd years for another Jedi order to spring up. So while Vader didn't kill everyone, he did a very good job of killing enough of the order itself that the most Jedi like person post-ROTS is a farm boy who hit Master largely because he was the only one left alive to be one.