We had lots of rivalries back in Vanilla. They were starting to brew in Classic but the release of cross realm BG’s killed all server community. At least in Vanilla with server only BG’s, the rivalries extended into battlegrounds, which made it WAY more fun than queing into randoms on cross realm.
Cross realm has killed all server immersion, servers are now pointless.
LOL, yeah, whenever someone asks about a good server and RP-PvP is indicated, the Deviate Delight folk come swarming in bashing Grobbulus. The Grobb Mob is more chill, and are more likely to recommend trying both and deciding which you like.
If there are, I’d expect it to be things like private server players against streamers, or the like. Somewhere that large amounts of the population have some identity they think is relevant.
There is, obviously, the anti-Heartseeker crowd - all the Horde-heavy PvP realms whose targets took the free transfers.