Will it be advisable to allow salesforce user creation through integration from a Third party legacy system.
Regards
It depends on (1) longevity and (2) role of the legacy system. For example: If the legacy system is the master system for users (such as Microsoft AD) and if it is a system of strategic value or/and if it going to be around for a while, then creating users in Salesforce based on the legacy system is not a surprising option.