Responses
I think this author is just creating their own version of an omgeaverse. Most omgeaverse are like what you described. I believe this author is just having it so alphas can't be with other omegas for this universe.
beta
Can’t marked alphas impregnate another omega?
Don’t alphas usually mark their omega and the omega depends on their alpha whereas the alpha can mark multiple omegas ? (づ￣ ³￣)づ