Why does Wikipedia block vpn?

Reliable VPN services from https://diadiktiokaiasfalia.com/

To enable the article-owners to better protect their property from "unwanted" editing and to identify, isolate and ban perpetrators.

To prevent trolls, and idiots, from making alterations to documents that already exist, and to prevent them from posting things that have no validity.

They block VPNs from editing because they have too high a potential for abuse. Hundreds of thousands of people could use the same VPN to edit anonymously. So you have to either block them or allow them to vandalize the site without recourse. AFAIK, they don't stop existing accounts from editing on them, though they usually prevent anonymous users from creating accounts on them.

Revealing your IP to Wikipedia doesn't show a whole lot, except what ISP you're using and your general geographical location. And you can hide that from everybody except administrators by creating an account. Even administrators cannot look up your IP without going through a specific process to determine that it is necessary.

https://en.wikipedia.org/wiki/Wikipedia:CheckUser