This is not entirely true. From the Google Translate site:
Thus, the actual translation service will still work as before, but a feature that allows the user to view his/her "history" (previously made translations) will require that the user has logged in.Upcoming changes to history
Translation history will soon only be available when you are signed in and will be centrally managed within My Activity. Past history will be cleared during this upgrade, so make sure to save translations you want to remember for ease of access later.
Note: To reduce cross-site tracking and protect user privacy, my browser (Safari) deletes tracking cookies, which apparently includes the history data, so the history feature doesn't work for me anyway...