Not Jacob, but IME from the past few years:
Generally, project ideas were expected to come with a list of potential mentors. I believe this ensures that projects which students apply to can be mentored if those applications are successful. Otherwise it wouldn’t be fair to students who put in the time to create an application + do any prereq work to qualify.
Another thing is that many (most?) projects list multiple mentors. In practice, there are only one or two mentors actually working on a project, and there is a large amount of co-mentoring. e.g. I don’t have bandwidth to supervise a project, but I can advise on or act as a backup mentor for yours. Or both of us are primary mentors on separate projects, but we act as co-mentors for the other project.