it's literally not,
in the merethic era, the dragons abused the power of the voice and used it to torment man. the leader of these rebellious dragons was of course, alduin.
kyne pitied man, and told one of alduin's lieutenants, paarthurnax, to betray alduin and teach man how to use the voice.
if you're not an idiot an did not kill paarthurnax, you could definitely teach stormcloaks how to use the thu'um |