GameMode variables - replication settings confusion

While beginning to dive into the adventure of network multiplayer, I found some strange thing in the Blueprint Editor. I have derived my own GameMode class and really wonder, why the Details Section offers the replication dropdowns for my variables. GameMode is living only on server, so where should this replicate at all? Isn’t this a bug in the editor?
Somewhat similar, in the Widget Blueprint Editor, variables also get offered these settings. As far as I understand, these only live on the owning client, also no sense in replication.
At least, this contributes to confusion about the topic of multiplayer.