On the client side how did they do this? I worked with a team reverse engineering another MMO a few years ago and it was because of a plain XML config and game launch args that we could make the client connect to a private server easily without modifications. Blizzard could just implement DRM and put an end to all this, right?
When I played on a private server, you used an old version of the client binary. So even if Blizzard implemented DRM now, it wouldn’t impact these old versions.