Why can't the users be merged together?

Our system is set up to where each user has his/her own dashboard settings. Therefore, it cannot be merged together. However, the primary user on the account does have the option to toggle in between accounts so that he/she can view the dashboards of other users to have access to their messages, RFQs that they have marked for quoting and RFQs that they have submitted quotes on. The primary user will be able to have full access to the account(s) of his/her additional users.