One of the considerations due to #7 is that legal and ethical issues should be taken into consideration. In general, what is being considered here is a platform for user-created content. Ownership of this content should be clear from the beginning; for instance, if an user deletes their library (#48), what happens to their votes? Depending on the recommendation engine, losing those recommendations might be a problem, or they might have been used already and it might not be. Either way, clarifying at every level what user-created content is used for and what rights are affected is very important.
One of the considerations due to #7 is that legal and ethical issues should be taken into consideration. In general, what is being considered here is a platform for user-created content. Ownership of this content should be clear from the beginning; for instance, if an user deletes their library (#48), what happens to their votes? Depending on the recommendation engine, losing those recommendations might be a problem, or they might have been used already and it might not be. Either way, clarifying at every level what user-created content is used for and what rights are affected is very important.