This has come up before in the tvtropes discussion thread, but personally I operate on the assumption that apparating in a combat situation is simply beyond the skills of most wizards. It requires deliberation, which is probably hard to muster when someone is firing death beams at you, and if you tried it you'd probably get splinched. It's probably doable for really exceptional wizards, like Voldemort or Dumbledore, but not for your average auror, let alone the average joe wizard.
Highly tactically useful feats that are extremely difficult to perform would be one major reason why some wizards can be so much more dangerous in a fight than others when wizards far from the top of the scale are capable of firing death beams.
There's also the Floo.
Edit: New thread posted here.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 86. The previous thread has long passed 500 comments.
There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16.
As a reminder, it’s often useful to start your comment by indicating which chapter you are commenting on.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: