You may have a different use case than ours.
1) Users in our system may log in and have a "free account" created through SSO, so there are a lot of "mistaken" logins, where for example, users mistake Workday and Workfront (next to each other on the list).
2) I usually try and keep the system cleaner. As workflows age out or get abandoned, we often delete the objects representing the workflow. e.g. a workflow may have had teams, forms, templates, and projects, issues and tasks created. But if through a reorg, the working team is laid off, all of these objects become redundant. So we first delete the projects, issues and tasks. After this, templates, teams and forms (as an example) also show up as being "unused" since we deleted everything using them. Additionally, users start showing up as having a "zero footprint" since we deleted everything that they had been assigned to. It is at this point where you'd have an opportunity to start deleting users.
I have inherited several instances now where this has been the case -- running reports to discover that it has been some years since particular custom forms were used, or discovering that they were never used (instant delete, and if it has been years since they were used, I request the governance team to make a decision for deleting it). After a brief spate of deletion, I usually find user profiles can then be deleted. Your mileage may vary.
