I’m sure they don’t want anyone to cancel their subscription, but it would be a bad business decision to spend an inordinate amount of resources trying to retain a minority of subscribers (DF Raid is 9% vs M+ at 19% and PvP at 16% per this BLUE POLL). Of that 9% that prefer DF Raiding, those that do Mythic is an even smaller percentage.
Race to World First? Outdated “server identiy/pride”? Who knows, it probably should be cross-realm (and cross-faction) from the day Mythic Raid opens, but the devs seem to think that would be bad for the game, until “enough” server-based guilds have completed the Raid. It used to be an equal amount of both factions but Horde so outweighs Alliance at Mythic Raid kills, that they relented and just made it 400 guilds total, rather than 200 of each faction (maybe that’s a season-by-season decision and not a new standing rule).