High Ground This!

Anakin has unlocked the High-Ground Counter

High ground was never really the issue in this scene. "High Ground" wouldn't protect Kenobi from what Anakin can actually do, the only thing protecting Kenobi from Anakin is plot armor. Remove the plot armor and let Anakin do what he is capable of and Kenobi doesn't walk away from this, Anakin does.

I see

Check these out. They show Anakin prevailing in that scene by doing what he can do.
imgflip.com/i/7xfcju
imgflip.com/i/7y7don

Anakin's rage blurred his rational thinking, causing him to simply leap into action instead of strategizing, something Anakin always struggled with, but was emphasized by his sithly rage. Obi Wan was quite a powerful jedi anyways, and being Anakin's master, Obi Wan knew more about how Anakin thought and fought than any other Jedi (possibly excluding Ashoka). Obi Wan was not saved by plot armor.

Well, Anakin had to survive that scene too in order to become Darth Vader. So the only reason he survived the lava is because of plot armor. Plot armor exists for every main character. That’s why stormtroopers are known as such lousy shots. Because they never hit the main characters.