This makes Boston/NY or Army/Navy seem tame in comparison.
^ I liken it to a religion.
One of the very few worldwide rivalries to Bama/Auburn is Celtic-Rangers in Glasgow, and that one literally
is religion.
Part of the issue you have in Alabama is that there's no other unifying factor for the fan base to rally around, and there's no other division other than the Bama/Auburn divide.
Here in NC, you have the three-headed State-UNC-Duke rivalry, with an extra dose of Wake/ECU fans jumping in on occasion. But you also have all of those fan bases pulling for the Panthers or Hurricanes when pro sports come into the discussion.
In SC, there's a clear Clemson/SC divide, but there's a big chunk of prominent people in the state that went to The Citadel, and two of the key media markets are tied to out-of-state teams (Charlotte/Rock Hill and Augusta/Aiken)
In Louisiana, LSU dominates everything, but you also have the Saints as a unifying factor statewide.
In Mississippi, neither Ole Miss nor MSU has regularly played for high enough stakes to really make the rivalry worth caring about, and Southern Miss has been the better football team for loooooooong stretches of time.
In Tennessee, the UT-Vandy rivalry was pretty one-sided for a long time, but the state is so geographically spread out that the fan bases can avoid each other pretty easily (and they all ignore Memphis) and that was before pro sports started to seep into the state.
Up in Virginia, the UVa-VT rivalry is pretty good, but not all-consuming when a huge portion of the population is transient or transplant w/ DC & Tidewater.
The Kentucky-Louisville rivalry is mainly hoops-focused, but they aren't in the same conference, and haven't regularly played each other in literally every single sport for 5 generations.
So in the state of Alabama, you've got a combination of insane fans, tight proximity, dearth of alternatives, generational hate, repeated competition, and high stakes that all add up to a total cocktail of crazy.