The "Account activity" log shows changes made by (and applied to) users identified by their email addresses.
Certain teams use universal emails or ID-based emails, such as "ab123@xyz.com" for SSO-based provisioning and login processes. It's hard to identify which user(s) are affected without also being able to review their names, and requires using a v-lookup or other reference outside of Aha! to double-check.
In addition to listing user emails on this screen, the user name can also be listed. This can potentially just be included in the CSV export as well to save space.