I completely agree with you on principle, and i don't expect or even want every mythic to be on the level of Famine or even Gards Avatar for that matter.
But there is a huge gap between the outlier Famine and several other mostly useless base mythics like Jotnar Wulfgarok or Stonehammer. Those base mythics spells could be buffed(changed) significantly without even coming close to Famines level of power. There is definitely a sweetspot to be hit without contributing to the power creep and still make base mythics feel exciting or at least useful.
Ironically the coming dragon mythic looks to be both, exciting and strong enough without being too powerful, while also fitting greatly thematically and gameplaywise....you know because Dragons desperately needed just another great troop, as if they weren't already the best designed, most versatile and most functioning single troop type in the game. Meanwhile lets completely mess up just another giant or dwarf, cause who really cares about them right?