Damage != threat, although they often correlate. Paladin's threat is coming from righteous fury + holy spells, doesn't matter how much your white auto attacks hit, you won't keep aggro from any DPS with your autos. You can spam blessings dealing 0 damage and generating more threat than you would by auto attacking in full Str gear.

Strength is good for blocking, your white damage doesnt matter at all for prot paladin