I find that explanation utterly unconvincing. Sword fighting isn't all about parry-riposte-repeat, a lot (most?) of it is about footwork. We saw this in Episode I, when Darth Maul kept on the move, choosing the time and location of his full-on engagement. We saw it in Episode IV, when Obi-wan retreated to the hangar bay in the Death Star hoping for a chance to escape. We saw it in Episode V, when Darth Vader three times (at least!) forced Luke into a position from which he could not fight. We saw it in Episode VI, when Luke used the obstructions and the dead drop in the Emperor's Throne Room to launch a surprise, and nearly fatal, attack on Vader. A lightsaber fight was always fought with the intention of moving from a disadvantageous position to a favorable position.

In contrast, the RotS duel was simply two people trying to murder each other. At the end, a stroke of luck (the Force

) put Obi-wan on the high ground, as he so helpfully told the audience. You know, just in case we missed it. And then Anakin, who is evidently so in tune with Obi-wan's thinking that, you know, neither can hit or even beat/parry the other, leaps at Obi-wan and gets cut to pieces. Because he knew that's exactly what Obi-wan would do, and when you know what your opponent will do, you never try to use that to your advantage.

Merry Christmas, and may the Force be with us, everyone.