trinity force also has a terrible build path where practically the only benefit is Sheen and is the most expensive item in the game. most champions have around 90+ base AD total
While it is a very impressive item for burst damage, it will very rarely be acquired first. Jax is one example, but his issue is more from runes than the champion himself
stormrazer is probably a decent pick on him as well for extra burst/AD/AS
i've been away from the game to really argue for strategy and such, but you also have to be within garen or darius's melee range to take the full damage and have to account for their cooldowns. Garen will get the most use out of it from his Q
if we compare the result though, let's say a champ has 70 armor at level 18 100 / 170 = roughly 59% damage taken or for everything hat he dished out including his Q, only about 282 total though the Q damage would add onto this
at level 18, 282 about 16% of your hp and then whatever the Q adds on
if it's 250, that would bring it up to roughly 150 extra damage or 430 total
though after looking that the wiki, garen's numbers are high. 142.5 AD at level 18 or 570 + Q in one AA reset
570 + 150 = 720 * 0.6(though low by some champs, caitlyn specifically who has over 80 armor)
432 damage or just over 20% of the standard marksman 2000
of course, they could have other sources of AD, but I do not have that information