There are many reasons why second person is the go-to point of view for first drafts. It is the most informal and conversational. Students tend to write like they talk, so second person is natural. They also read a lot of second person online; advice articles, how-to, and informal blogs tend to use second person.
Second person, however, is the point of view that should be almost never used in academic writing. Besides the informality, which is inappropriate in a research paper and other academic essays, the main reason second person is not preferable is because it excludes or alienates part of the audience.
I use a few humorous examples to show this, and that is when it usually clicks with students. For example, I first ask the students, "Who is the audience for this paper?" The typical answer is me, the teacher, but we also discuss that it is anyone who is interested in the topic. Then I read the following passage from a student paper about preventing teen pregnancy:
"You should discuss your sexual activity with your parents or another adult because studies show that if you do this, your chances of pregnancy go down significantly."
I ask the students if I should discuss my sexual activity with my parents or another adult. I also ask a male student if this advice will help reduce his chance of pregnancy. Of course they immediately understand my point, and we don't need to elaborate on how second person excludes part of your audience.
We also review how the tone of this passage is more like a self-help article than academic research. Then I show a simple rewrite:
"Teen girls who discuss their sexual activity with their parents or another adult have a significantly reduced rate of pregnancy" (Smith 21).
There will always be the ubiquitous "you" in student papers, but a simple example requiring students to think about their audience will help them revise correctly.
If you are looking for resources to teach point of view, here is the Power Point and rewriting exercises I use with my classes: