Is the Purge Re: Prefixes option in the dashboard obsolete?

[rich20]

Describe the bug
We have the Purge Prefixes option in the Dashboard -> Tools (see image below). But you cannot remove prefixes with this option.
Message: No message subjects starting with 'Re' were found.
I think that was an option for K3, where every title in an answer started with Re. Now we have ‘Replied by’ and username.

We only have Re-prefixes on the index page and you can disable these prefixes in the configuration (Frontend tab).
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