Not necessarily true. It depends on how your character is developed and how you use your troops.
Archdemons have no resurrection, yet due to their fast initiative, with a Mage-Amelie you can cast invisibility and spell-nuke everything. But if you were a Warrior-Amelie, you wouldn't have enough mana to do this.
Black Dragons are great to help avoid enemy heroes from nuking you, yet again, more useful with the Mage-Amelie. Again, no resurrection or summon.
Trolls with peacefulness and stoneskin and at night might be one of the most deadly tanks out there. No resurrection or summon here either.
Range Style play requires the most damage output (basically, destroy the enemy so fast, they can't retaliate anyway). Too many summon units would hurt that sort of build. I only used paladins to help restore the ranged units en-mass. Another guy on here relied on skeleton archers (which cannot be resurrected by paladins), and royal griffins (which never work well for me).
So you can't assign a universal weight since I can make bowmen into the most powerful unit for my type of game play, yet they will be total junk in your game. Or someone will make black dragons incredibly strong in their game too.
About the only unit in the game with infinite resurrection is the double droid stack build. While you can set artificial limits on that, taking eons to kill the enemy alone is punishment enough in my book.
That's why I went with the ultra fast damage range team. Took out Ktahu in 12 rounds, impossible-mode, no losses.
But that is part of the allure of this game. Being able to maximize a unit's abilities to suit your particular game style. I think we need to simply introduce more viable gamestyles rather than artificially limit ourselves.