One of the best points for chalk over powerpoint is that it's easy to diverge from the script if you need to. A good teacher adapts to the needs of the student(s). Secondarily to this, chalk allows for a script that is more interactive to begin with (eg, "who can give me an example of an abelian group?" followed by verifying the axioms).
But, while powerpoint may be a fundamentally weaker medium, I think part of the problem is that a lot of people are simply bad at it. Having an optimal presentation requires a lot of attention to things like pacing, and separating content between the powerpoint itself and the delivery. I get the feeling that a lot of people don't look further than content. Hint: if you print your slides and distribute them as notes, they are not optimal for at least one of those purposes[1].
[1] However, optimal slides printed out with room to take notes during a lecture can often be made into optimal notes by a good student.
But, while powerpoint may be a fundamentally weaker medium, I think part of the problem is that a lot of people are simply bad at it. Having an optimal presentation requires a lot of attention to things like pacing, and separating content between the powerpoint itself and the delivery. I get the feeling that a lot of people don't look further than content. Hint: if you print your slides and distribute them as notes, they are not optimal for at least one of those purposes[1].
[1] However, optimal slides printed out with room to take notes during a lecture can often be made into optimal notes by a good student.