Yes but on reddit, upvotes puts something in your upvoted list and you can save selectively, which is a much better system for organization.
Boosts and upvotes have a slightly different functionality here that I do upvote and/or boost posts and comments differently, none of which is to add the post to my favorites. Even though it can be used that way for the same effect, it's a different use case.
What if I want to save a post I didn't want to boost or favorite? Should I not be able to save a comment I disagree with that I also downvoted?