What's the overall purpose for having Run As for learning initiatives?

Run As defines whose data security policy gets applied when initiatives and access groups are processed. You can set a global default and optionally let individual learning administrators override this setting per initiative or access group.

A generic Run As user ensures that initiatives and access groups continue to be processed, even if their original creator is no longer with the organization. And relying on a single Run As user doesn’t create bottlenecks or slow down processing. Each process always switch to a user for each initiative or access group, so the process always apply the appropriate data security. Switching to the same user or switching to each creator doesn’t make any difference.