Should R package functions not include comments?

Question

I'm in the process of creating a small R package containing a set of functions that should be useful in a specialized area of Biology. I currently have the package on GitHub, but want to submit it to CRAN soon. One thing I have noticed when digging around in other packages, is that the code often includes no comments at all (e.g. short comments describing what different parts of the code does), which makes it more difficult to understand. I'm not a programmer or expert in R, so I don't understand why comments are often not included, and Hadley Wickham's "R packages" book makes not mention of this.

Edit: I'm not referring to the object documentation, that one accesses with ?function(), but to comments that are interspersed within the function code, which a normal user wouldn't see, but that could be helpful for people trying to figure out exactly how a function works.

Is there a specific reason to not include comments within the functions of an R package? If so, should I remove all the comments from my code before submitting to CRAN?