Sysops can set an IP block exempt group for other users (including themselves) in their local wiki. The procedure is different in different wikis, but for example, in Finnish Wikipedia, you need to ask for it, and the admin will add you to the group if you have a reasonable reason, such as the user is using a VPN. Basically, everybody who has been asking for the IP block exempt flag is using it well.
However, VPNs are also commonly used to avoid blocking and masking problematic behavior patterns, including editing warring, ignoring other users, causing personal attacks, and hounding. So, it is not only about protecting the editor using a VPN but also about protecting other users from unsuitable behavior made through VPNs.
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